Dan Margulis Applied Color Theory
RGB Numbers and Workspaces
Date: Tue, 14 Oct 2003 19:41:11 -0000
From: Holly Thorne
Subject: RGB Numbers
Been reading along here...charming stuff.
I want to just clarify something so my head is screwed
on right. No matter what color space I use (sRGB, Adobe RGB, etc.), my
colors are represented by the same numbers 256x3 channels (unless I am
working in 16 bit). SO...I am wondering: when someone refers to Adobe RGB
as a 'broader color space' just how is that? I mean if it is using the same
numbers and represents different colors, it really has the same number of
colors -- it just represents them differently?
Not to throw a glass beaker over a rock driveway, but
doesn't that deflate the importance of the working color space a bit? If my
monitor doesn't display Adobe RGB, I can choose to safely view in sRGB and
don't have to futz with profiles, because sRGB will probably be assumed by
most devices. No? So here I am with my sRGB image going to an sRGB device
(another monitor) and voila...sRGB. Difference would be calibration --
which would be a variable anyhow.
If I take that same sRGB image and tell PS about my
monitor in a profile (not so as to embed it), and then choose to proof on
screen, I can see some previews for generic web and sheetfed without $$
spent on custom profiles. Blimey if these don't end up pretty close. I
convert to CMYK, and then I have CMYK, and it looks like CMYK, smells like
CMYK...separated for my target. At this point, with CMYK, I don't bother
embedding a profile because it shouldn't matter. If I have prepped my CMYK
file for CMYK output to a specific CMYK device, then I am not changing
anything by telling the printer "hey, printer, I am sending you a CMYK
file separated just for you." I don't re- profile a target I have
already profiled for. Snurks to custom profiling...I get that you want to
customize to specific printers and inks.
So, just thinking aloud, mind you, if I just stick with
sRGB and don't try to get fancy-schmancy and use standard printing stock
etc., I get color I can be happy with without all the profile-potential-
hang-me-ups and complications.
Is all that about right? If not, please don't start a
war on my account but just tell me what's wrong in the second paragraph?
I'll suffer the rest.
Holly Thorne
___________________________________________________________________________
Date: Tue, 14 Oct 2003 16:54:01 -0600
From: Andrew Rodney
Subject: Re: RGB Numbers
on 10/14/03 1:41 PM, rgbvitality wrote:
I want to just clarify something so my head is screwed
on right. No
matter what color space I use (sRGB, Adobe RGB, etc.),
my colors are
represented by the same numbers 256x3 channels (unless
I am working
in 16 bit).
No. The same color appearance can be produced with
different sets of numbers in different RGB Colorspaces. The same numbers
produce different appearance too.
Not to throw a glass beaker over a rock driveway, but
doesn't that
deflate the importance of the working color space a
bit? If my
monitor doesn't display Adobe RGB, I can choose to
safely view in
sRGB and don't have to futz with profiles, because sRGB
will probably
be assumed by most devices. No?
Nope. You think your monitor IS producing sRGB and for
that reason you don¬πt need to profile it? Not the case.
So here I am with my sRGB image going
to an sRGB device (another monitor) and voila...sRGB.
That¬πs in a perfect world. Output devices and
capture devices can¬πt really be natively be in sRGB as sRGB
isn¬πt even based on a real device and if it were, it be a very
simple monitor like device since Working Spaces only need three sets of
values to be defined (a Gamma, whitepoint and chromaticity values).
If I take that same sRGB image and tell PS about my
monitor in a
profile (not so as to embed it), and then choose to
proof on screen,
I can see some previews for generic web and sheetfed
without $$ spent
on custom profiles.
IF indeed those devices behaved as you¬πre
predicted.
I convert to CMYK...
Using a profile!
At this point, with CMYK, I
don't bother embedding a profile because it shouldn't
matter.
Correct. Unless you want someone to open the file and
see how it appeared to you.
So, just thinking aloud, mind you, if I just stick with
sRGB and
don't try to get fancy-schmancy and use standard
printing stock etc.,
I get color I can be happy with without all the
profile-potential-
hang-me-ups and complications.
IF indeed those devices behaved as you¬πre
predicted. Another emphases on ³IF².
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Thu, 16 Oct 2003 04:47:46 -0000
From:Randy Wright
Subject: Re: RGB numbers
Adobe98 is to sRGB as inches are to centimeters. 10
inches is not the same as 10 cm. You can measure any length(color) in
inches or centimeters, but the numbers defining that length(color) will be
different. Also, 256 inches is a greater length(range of colors)than 256
cm, but you can make finer distinctions between the steps(colors) in the
metric scale.
Randy Wright
Color Services
___________________________________________________________________________
From: "Mike Russell"
Date: Fri Oct 17, 2003 2:24 am
Subject: Re: [colortheory] RGB Numbers
Holly,
I'm in agreement with you. There's nothing wrong with
your second paragraph, except that it's probably redundant to tell the
emperor he has no tie, when in fact he is not yet ready to accept the
notion that he has no clothes at all.
There is less need for profiles than is often touted,
particularly for a small set-up of one or two systems. For me, the main
challenge of color correction is the adjustment of color to achieve a
significant effect in the final image, and this is not facilitated by
over-accurate calibration and profiling, and may in fact be hindered by it.
Good quality digital pictures were happily being made
before profiles existed, with very relatively little effort put into the
issues that profiling is designed to solve. The tangible progress in color
correction has been, I submit, not accuracy and reproduceability but
improvements in equipment speed, capacity, and cost.
I'll go one further and say that we are acting out,
through our controversies over whether and how much to calibrate, an
ancient psychological battle. Mankind has ever been split into the
Dionysians, who follow a devil may care attitude about everything, and the
Apollonians, who are forever striving to bring order the world.
Balance is key, and in fact each of us embodies aspects
from both personality types. Too much Dionysius, and everything is a mess.
Too much Apollo, and we're spending too much time staring at patches and
sticking suction cups on our monitors.
Mike Russell
http://www.curvemeister.com
http://www.zocalo.net/~mgr
http://geigy.2y.net
___________________________________________________________________________
Date: Fri, 17 Oct 2003 08:00:17 -0600
From: Andrew Rodney
Subject: Re: RGB Numbers
on 10/17/03 12:24 AM, Mike Russell wrote:
I'm in agreement with you. There's nothing wrong
with the second paragraph,
except that it's probably redundant to tell the emperor
he has no tie, when
in fact he is not yet ready to accept the notion that
he has no clothes at
all.
More Dan speak?
Good quality digital pictures were happily being made
before profiles
existed, with very relatively little effort put into
the issues that
profiling is designed to solve.
Great color WAS made before profiles. The question was,
how many rounds of proofs were needed, did anyone looking at the image have
any idea of what they were looking at was remotely close to what they1d get
off the printer. Control over gamut mapping was virtually non existent and
taking the same RGB data (if you could even get it) and producing multiple
files for multiple devices was near impossible (unless you wanted to burn
more time and money at the print stage).
Profiles don1t do anything but describe stuff. When you
describe what the display is going and what the numbers in the file really
mean (they are after all just numbers), it makes it a lot easier, faster,
cheaper and more consistent to get the good color. Profiles don1t magically
produce numbers that are correct to produce great color. Profiles allow the
user to see and then get the color they want. If you1re happy making prints
then corrections until you get to your aimpoint, you don1t need a profile.
But I prefer NOT to use a kitchen knife as a screw driver when I have a
power drill!
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Sat, 18 Oct 2003 10:20:47 -0400
From:John Castronovo
Subject: Re: Re: RGB numbers
Randy,
In your analogy, one can measure the same distance with
either inches or centimeters, i.e. the numbers are different, but the thing
being measured is the same.
However, the difference between sRGB and Adobe98 (or
larger color spaces) is that the size actually increases and not just the
numbers measuring it. The reddest red is redder in one than the other, so
given that there are only 256 numbers to represent red, a one unit change
in sRGB means less than it does in a larger space.
Maybe you were trying to say the same thing, but I
thought that the analogy could be misleading to some.
john castronovo
___________________________________________________________________________
Date: Sat, 08 Nov 2003 13:43:38 -0000
From: "rgbvitality"
Subject: Re: RGB Numbers (round 2)
I'm back after a little leave...I just wanted to
clarify, and thank those that responded. I still have a quandry, and really
want to understand...
I'm in agreement with you. There's nothing wrong
with the second paragraph,
except that it's probably redundant to tell the emperor
he has no tie, when
in fact he is not yet ready to accept the notion that
he has no clothes at
all.
So...I have 256x3 colors in sRGB or AdobeRGB. These
colors map something different. Using the measure analogy, say the
following represents broadness of a color space:
sRGB:
| | | | | | |
| | | | | | | |
|
Adobe RGB:
| | | |
| | | | |
| | | | |
| |
The color range for Adobe RGB is somewhat broader.
OK...Size is said to be impressive, but what does it really mean? As a girl
size hasn't always been a motivation, regardless of what you hear.
So, I view this on a screen that is neither sRGB or
Adobe RGB...it is Monitor RGB.
say Monitor is somewhere between sRGB and Adobe RGB:
| | | | |
| | | | | |
| | | | |
The representation of either of these is skewed, unless
it falls within the range of my monitor...If I can't see the 'big end' of
the Adobe RGB, and it represents a color outside my monitor gammut, that
will pretty much be re-assigned to something else, and I won't see it
correctly. yes? Like a flat conversion from RGB to CMYK, I get trunctated
results just from viewing on screen! If I use sRGB, the color will pretty
much be guaranteed to fit my monitor, and I see all of it...no skewing.
This is if I don't
calibrate. yes?
Monitor RGB:
| | | | |
| | | | | |
| | | | |
sRGB:
| | | | | | |
| | | | | | | |
|
Adobe RGB:
| | | |
| | | | |
| | | | |
*|* *|*
*color in trouble*
Now, I've viewed on screen. If using Adobe RGB for
correction and having been a good girl and calibrated my monitor and
generated the ICC profile, the numbers get corrected for the space of the
monitor. That is sRGB and Adobe RGB remap for the screen based on the
profile...
Monitor RGB:
| | | | |
| | | | | |
| | | | |
sRGB:
| | | | |
| | | | | |
| | | | |
Adobe RGB:
| | | | |
| | | | | |
| | | | |
As far as i understand the profile is supposed to
translate so as to optimize color to the device. If i have 256x3 colors,
then that is all I have. A good profile works with those limitations to
display what I actually have optimally. NO? If that isn't the way this
works, then I am not sure what the point is if the mapping isn't going to
show me a changed representation of all the colors and adjust according to
the device profile? In the end, broad or short, whichever the color space,
I see the same thing if i choose a working space and have a monitor
profile.
If this works as i have stated, then corrections should
lead to the same display if there is an optimal appearance. If this does
not work the way i have stated, then the Adobe RGB will represent all sorts
of colors I can't see -- and can't judge the meaning of reliably in
preview. However, if it DOES remap, the same representation of sRGB and
Adobe RGB on screen will mean different things as mappings -- if the
numbers can be interpreted differently -- that is IF the printer knows the
profiles the result is based on.
so...i go along with the assumption it has to re-map
for the preview...not change the numbers of the file, but to show me
Monitor RGB representations of each file.
I take my identically corrected sRGB and Adobe RGB
images, and decide I want to print.
If i work in RGB having built the Monitor profile, I
see the colors mapped to the Monitor RGB on screen. if I send sRGB to press
with no profile, I should get a CMYK conversion of these
colors...unpreviewed, the results would probably diminish RGB>CMYK.
However, converted to CMYK before sending (to a printer that respects my
CMYK) I will get what i send, and preview my CMYK via my Monitor RGB. This
is the only time this happens: No profile embedded, no real surprises. If I
send sRGB with a profile for the working space, that space should adjust to
the CMYK--IF the profile is respected. If not, profiling does nothing. If
it adjusts, I SHOULD get somewhat better results by filling the CMYK
gammut, depending on the quality of the mapping. HOWEVER, if these are
drastically different, there might be compression in various ranges...who
knows what you really get. I could get equally surprised by a profile than
not having one. It depends on how that conversion is made. But comparing
the workflows, it seems a smarter move to do one of the following:
sRGB>CMYK
sRGB>embed sRGB profile to send RGB to CMYK device
Well, so I keep following the string...If I work in
Adobe RGB and send Adobe RGB to press with no profile, the numbers will
probably be seen as sRGB. The response -- because there is no translation
-- will be seen as sRGB, and the result will probably be FLATTER than
working in sRGB with no profile because the sRGB representation will be
compressed. No? I wouldn't optimally correct the image in a different way
just because the numbers tell a different story. On the other hand, I stick
the Adobe RGB profile in there and send RGB, the device should read the
profile, understand the representation of Adobe RGB, and the result might
seem to bloom on press. The colors I can't see get translated to the CMYK
space and just the opposite of what happens without a profile happens with.
That might be a blooming surprise of over-saturated color...Again,
depending on how the color is translated. rreally, if all is working
perfectly, sRGB correction should MATCH the AdobeRGB --that is IF EACH
IMAGE HAS BEEN OPTIMALLY CORRECTED. Regardless of the working space.
If any of this is correct, i need a profile embedded to
benefit from Adobe RGB...HOWEVER, why do I need Adobe RGB at all? if the
goal of profiling is to match screen to print, then profiles will work with
either sRGB or Adobe RGB to give me the same match from my screen to
printer...regardless of the working space. Looking back at the non-profile
results, adobe RGB only ends up in flatter images when profiles are not
respected, so what benefit is there to Adobe RGB in imperfect situations?!
It seems the best choice is to work in sRGB, in either
case.
if i have someething fundimentally wrong, I'd be glad
to know so I can rethink what i
do.
Holly Thorne
___________________________________________________________________________
Date: Mon, 10 Nov 2003 11:23:03 -0800
From: Alison Walker
Subject: Re: Re: RGB Numbers (round 2)
Holly,
I am very impressed with how you have been able to
demonstrate the
issues of out of gamut colors visually in an e-mail.
You are on the
right track. There are two more graphs you need add,
CMYK and Lab.
CMYK SWOP Coated 320 dmax
| | | | |
| | | | |
|
sRGB
| | | | |
| | | | |
| |
6 color Epson
| | | | |
| | | | |
| | |
Monitor RGB
| | | | |
| | | | |
| | | |
Adobe RGB
| | | | |
| | | | |
| | | *|* *|*
*|*
Lab
| | | | |
| | | | |
| | | | |
| | | |
|
* out of gamut colors relative to smaller color spaces
Profiling is a way of providing a definition of the
"flavor" of color that is represented by the numbers found in a
color space. A red might visually look the same in two different files but
numerically they may be different if they are from two different color
spaces. Or they my have the same RGB values but display differently
relative to there color space. The job of the profile is to move colors
between color spaces. If a smaller space does not have a particular flavor
of color as in a larger space, the conversion process will figure out how
to move that color into the smaller space.
Every profile has a table of RGB measurements taken
when the profile was made. It also has a Lab table representing those RGB
values. Because Lab has a larger color space than any device, it is used as
a translator between profiles. Additionally, the rendering intent (like
relative or perceptual) used to perform all this math will determine how in
gamut and out of gamut colors are transfered between the two profiles /
color spaces. The idea being that with profiles we can make
"choices" about how colors are converted from one space to
another. Managing the conversions to get more predictable results.
The idea of starting with a larger color space is
to try to capture as many of the original colors found in an image. This
way no matter what your final out put, you will have retained all those
colors to send to an output device assuming its gamut is big enough to
accommodate them. By starting with the larger space you are not limiting
your self if you change output devices sometime in the future. Your master
RGB file might still have colors in it that a larger gamut device could
handle. Note the difference between the CMYK and Epson output spaces above.
No matter what, as you convert between spaces you will
loose colors if they are out of gamut. The profile tries to keep colors
that are the same flavor (Lab) but with different RGB values looking the
same as they are converted as long as the flavor is contained in each
space. And converting from a smaller space back to a larger will not bring
them back. Once they are lost in a conversion, they are gone for good. But
trying to decide what color space to start with is the big question. My
feeling is if you can find a repeatable and predictable way to handle out
of gamut colors with one space better than another, that is the space you
should work with. Other wise you may be fighting with colors your output
device could never handle.
I find it best to send out files that are converted to
the final output device. That way I know how the conversion was handled and
if I have to make any changes I can redo the conversion the exact same way
as before. But if you are sending out RGB, they must have a profile
attached. Attaching profiles to CMYK is a little less critical but can be
helpful. Sadly, you can't always count on the person down stream knowing
what to do with some of these images. Find a vendor you trust. Talk
to them a head of time. Ask questions. If you don't think they understand,
either bring them up to speed or go somewhere else. But don't assume they
know more then you.
Good luck. Hope this helps.
Alison Walker
Seattle, WA
___________________________________________________________________________
Date: Tue, 11 Nov 2003 12:37:56 EST
From: Dan Margulis
Subject: Re: Re: RGB Numbers (round 2)
Holly writes,
Looking back at the non-profile results, adobe RGB only
ends up in flatter
images when profiles are not respected, so what benefit
is there to Adobe RGB in imperfect situations?!
Certainly one has to look out for such situations. We
recently had the longest thread in the history of the group, in which there
was a lot of heat but all the rational parties agreed that people need to
be extremely careful about who they hand their Adobe RGB files off to.
Since that time, there has been a major development in
Photoshop CS. The new default behavior is that embedded CMYK and grayscale
profiles are ignored, period. No warning, no nothing. This should,
hopefully, terminate the endless threads here in which we are advised that
embedded profiles are the wave of the future in CMYK and that it's all a
matter of educating users and that resistance is futile.
The RGB situation is similar. The new Photoshop CS
default is sRGB. Embedded profiles are honored by default, so if we receive
a tagged Adobe RGB file from someone else it will open into Adobe RGB
automatically, without any warning. Of course, many users will continue to
have settings that ignore the profile with disastrous results.
These changes concede the correctness of what I have
been saying for many years, since in effect what they are doing is
attempting to restore the pre-1998 status quo. IOW, what we've learned the
hard way since 1998 is that the world at large doesn't have a taste for the
"flavor-of-the-week" RGB and CMYK described elsewhere today.
Instead, we have in CMYK an explicit return to a vague standard. In RGB the
move isn't quite complete but it's been evident for some time that sRGB
will be the winner, and now it's a sure thing.
Also, in my classes there have been a surprising number
of recent cases where students brought in problem images caused by a misuse
of Adobe RGB. This past week there was a particularly egregious example.
The student's company produces food catalogs, the food being shot digitally
in a studio. Many of the items are brilliantly colored, such as corn or
various green vegetables.
Their workflow apparently calls for the photographer to
convert to CMYK before the color correction, which isn't a great idea IMHO.
But whatever, all the student had was uncorrected CMYK files. The color
basically looked good but wherever there was something brilliant all the
detail was almost completely gone. It was a real PITA to get it back.
While we don't know what went on in the studio, I'd bet
a large amount of money that the photographer was using Adobe RGB or
something even wider-gamut. Thus, he had a lot of out-of-CMYK-gamut colors
while in RGB, and when he converted, no matter what setting he chose, he
was booked to wipe out detail in bright colors.
The setup was apparently well calibrated, so all the
photographer had to do was assign a false profile of sRGB to these
particular images and all would have been well. Instead, there was a mess
that took a long time to fix.
In summary, Adobe RGB is perfectly viable but those who
want to use it need to 1) understand that the rest of the world isn't
necessarily on the same page and that precautions will be necessary before
passing the files on to strangers; 2) understand how to assign a
narrower-gamut profile if necessary for certain images.
Dan Margulis
___________________________________________________________________________
Date: Fri, 14 Nov 2003 09:44:16 -0600
From: Lori Sabo
Subject: Re: Re: RGB Numbers (round 2)
Dan,
Does that mean you can't convert correctly from a cmyk
file to other
cmyk spaces or to rgb spaces (as in, convert to
profile)?
Lori
___________________________________________________________________________
Date: Fri, 14 Nov 2003 16:30:31 EST
From: Dan Margulis
Subject: Re: Re: Re: RGB Numbers (round 2)
Lori writes,
Dan,
Does that mean you can't convert correctly from a cmyk
file to other
cmyk spaces or to rgb spaces (as in, convert to
profile)?
No. All color settings behave exactly as before, as do
the Assign Profile and Convert to Profile commands. The change is that the
new *default* is for CMYK embedded profiles to be ignored altogether,
although we are free to change it to something else if we like. Thus, we
finally have an end to the interminable debate on this list as to whether
CMYK embedded profiles will ever become so entrenched that we would be able
to trust strangers to honor them. But, if you have something that works for
you in Photoshop 7, just load it into CS and continue to do what you're
doing.
Dan Margulis
___________________________________________________________________________
Date: Fri, 14 Nov 2003 16:25:08 EST
From: Dan Margulis
Subject: Re: Re: CMYK on RGB only devices
Hal Silverman writes,
Command-Option-~ (tilde)
What is the selection that is made based on?
A grayscale version of the document, created internally
and loaded as a selection without ever becoming visible to the user.
Dan Margulis
___________________________________________________________________________
Date: Sun, 16 Nov 2003 13:36:09 -0700
From: Chris Murphy
Subject: Photoshop CS defaults, was: RGB Numbers (round
2)
On Nov 11, 2003, at 10:37 AM, Dan Margulis wrote:
Since that time, there has been a major development in
Photoshop CS. The new
default behavior is that embedded CMYK and grayscale
profiles are ignored,
period.
That's always been the default behavior. In Photoshop 6
and 7, the default Color Settings was set to Web Graphics defaults, which
causes all of the color management policies to be Off by default.
The RGB situation is similar. The new Photoshop CS
default is sRGB.
That's the same as it's been since Photoshop 5.
Embedded profiles are honored by default, so if we receive a
tagged Adobe RGB file from
someone else it will open into Adobe RGB automatically,
without any warning.
Of course, many users will continue to have settings
that ignore the profile
with disastrous results.
Yes, this is what's new. The "General Purpose
Defaults" for North America, Europe, and Japan. The color management
policy for RGB is now Preserve Embedded thus RGB editing spaces will be
embedded into files when saved, and embedded profiles will override the
working space automatically when opening files.
The other change is that the rendering intent has been
changed to Perceptual which I think is a bad idea. If it's used in
conjunction with the default CMYK profile from Adobe it will result in
nearly identical conversions as RelCol in particular in the case of SWOP.
This is not how most profiles behave. Most of them have a bit of a contrast
and midtone boost in the perceptual intent as compared to RelCol. If this
were the case with the U.S. Web Coated (SWOP) v2 profile, I wouldn't object
as much because as previously discussed on this list the Adobe SWOP v2
profile produces darker separations than it should.
These changes concede the correctness of what I have
been saying for many
years, since in effect what they are doing is
attempting to restore the pre-1998
status quo.
Dan, two things have changed, let's not get carried
away. U.S. Prepress Default was never the default behavior in Photoshop,
and if you decide to select it, it has the same behavior as it has in
Photoshop 6 and 7.
Their workflow apparently calls for the photographer to
convert to CMYK before the
color correction, which isn't a great idea IMHO. But
whatever, all the student
had was uncorrected CMYK files. The color basically
looked good but wherever
there was something brilliant all the detail was almost
completely gone. It was
a real PITA to get it back.
I've seen this quite a bit in cases where Adobe RGB
(1998) was assumed to be the source profile for digital camera shots. I
think this is a bad idea. ColorMatch RGB, or Apple RGB in lieu of a more
appropriate profile for that camera, are a far better starting point than
Adobe RGB. Digital cameras don't have Adobe RGB behavior, so using it as a
source profile is probably not a good assumption. But as this has already
been discussed I'll leave it at that.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Fri, 21 Nov 2003 07:19:18 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Chris Murphy writes,
That's always been the default behavior. In Photoshop 6
and 7, the
default Color Settings was set to Web Graphics
defaults, which causes
all of the color management policies to be Off by
default.
"Web Graphics" was only the default if the
print-oriented user ignored several prompts to load something else. But in
any event, there's an enormous difference. Web Graphics would alert
whenever it encountered an embedded profile. Consequently, when there was a
screwup, those in denial about whether embedded profiles would ever catch
on had a convenient way to do what they do best, blame the user.
With Photoshop CS, there's no such excuse. The default
that most people will use ignores CMYK profiles altogether, no warning, no
muss, no fuss. It's a pure and simple acknowledgment of what I said in 1999
about where the failure of this concept in the CMYK community.
Yes, this is what's new. The "General Purpose
Defaults" for North
America, Europe, and Japan. The color management policy
for RGB is now
Preserve Embedded thus RGB editing spaces will be
embedded into files
when saved, and embedded profiles will override the
working space
automatically when opening files.
Again, what I recommended in 1998. It is gratifying
that Adobe finally sees the light.
The other change is that the rendering intent has been
changed to
Perceptual which I think is a bad idea.
Right. I was surprised at this, since earlier this
year, a couple of the more prominent Adobe bootlickers announced (in a very
gracious way, it must be admitted) that they had been mistaken all these
years and that Relative Colorimetric was probably best for most images,
thus joining me in a position I have taken since 1998.
I've seen this quite a bit in cases where Adobe RGB
(1998) was assumed
to be the source profile for digital camera shots. I
think this is a
bad idea. ColorMatch RGB, or Apple RGB in lieu of a
more appropriate
profile for that camera, are a far better starting
point than Adobe
RGB. Digital cameras don't have Adobe RGB behavior, so
using it as a
source profile is probably not a good assumption.
Shhh! Don't tell your color-management friends! Many of
them haven't realized the drawbacks of wide-gamut RGBs just yet. What would
happen if they have to surrender on this point too, after so many other
defeats?
I notice on the ColorSync list that there has been a
reversal of position regarding the practicality of profiling cameras,
something I was excoriated for being dubious about here only two years ago.
Now, it appears that everyone concedes the point. And not only have they
reversed their view of Photoshop 5, but most of them have gone beyond mine,
which they initially said was reactionary, prehistoric, etc. Not to mention
the relatively new acceptance of photographers doing their own CMYK, of
profiling proofs rather than presses, of digital cameras as
professional-quality instruments, of nonimpact printers as contract
proofers, and of emphasizing process control, in all of which areas they
are now chasing positions that I've held for a very long time.
Now, granted this cave-in on the embedded profile
issue, how would it be if they also started doubting Adobe RGB? In such a
disastrous scenario, the entire color management community would actually
have morphed completely, and not have a single position that can be
distinguished from I stood in 1998. What's next? Will they all grow
gray hair and become Margulis clones?
Dan Margulis
___________________________________________________________________________
Date: Fri, 21 Nov 2003 11:53:22 -0700
From: Chris Murphy
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Nov 21, 2003, at 5:19 AM, Dan Margulis wrote:
With Photoshop CS, there's no such excuse. The default
that most people will
use ignores CMYK profiles altogether, no warning, no
muss, no fuss. It's a
pure and simple acknowledgment of what I said in 1999
about where the failure of
this concept in the CMYK community.
Well, you weren't the only one saying it, but you were
in an elite club of people being ignored by Adobe on this front.
And really, the cave-in here is more an admission that
the user interface and intelligence in the application is insufficient.
Because what we really need, especially in a page layout application, is
not wholesale dropping of embedded profiles in CMYK images. What we need is
for the application to have a better understanding of what kind of device
the CMYK images is going to be printed on. Because if it's a press,
or anything that has less than perfect registration, yes we most likely
want to discard embedded profiles to avoid automatic repurposing. But in
the case where the output device has perfect registration, that isn't the
case. It's more often BETTER to repurpose those kinds of images and
illustrations. The reasons why we care about channel integrity in CMYK have
to do with the mechanical realities of the printing process.
Again, what I recommended in 1998. It is gratifying
that Adobe finally
sees the light.
Imagine how much less painful life would have been if
we'd just been able to get over this hurdle the easy way instead of the
hard way. And how we'd have three versions of Photoshop that behaved
sensibly by default instead of just one that's a month old.
And what's kind of perverse is that U.S. Prepress
Defaults, where we really need these sane behavior the most instead of
something vague like "General Purpose Defaults", *still* has the
Preserve policy for CMYK.
Right. I was surprised at this, since earlier this
year, a couple of the more
prominent Adobe bootlickers announced (in a very
gracious way, it must be
admitted) that they had been mistaken all these years
and that Relative
Colorimetric was probably best for most images, thus
joining me in a
position I havetaken since 1998.
I don't get it either. If Adobe had come out with an
improved SWOP profile, containing a perceptual intent to compensate for the
ICC spec's assumption of paper white being L*=100 (resulting in
increasingly excessively dark separations the darker the paper white is),
then I'd be OK with perceptual as a default while that SWOP profile was
also the default. If you want something better, change it. But in
actuality, the current SWOP profile produces 1-3% *darker* separations
using perceptual. So I think it's just a bad idea.
Shhh! Don't tell your color-management friends! Many of
them haven't realized
the drawbacks of wide-gamut RGBs just yet. What would
happen if they have to
surrender on this point too, after so many other
defeats?
There isn't a problem with wide-gamut RGB. The problem
is using them as an assumed source profile when the image came from a
digital camera.
Now, granted this cave-in on the embedded profile
issue, how would it be if
they also started doubting Adobe RGB? In such a
disastrous scenario, the entire
color management community would actually have morphed
completely, and not
have a single position that can be distinguished from I
stood in 1998. What's
next? Will they all grow gray hair and become Margulis
clones?
Oh stop it! You're going to start scaring people!
There's no need to be mean, Dan.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
________________________________________________________________________
Date: Sat, 22 Nov 2003 03:45:53 -0000
From: "David Kern"
Subject: CMYK Conversion Question
Sorry for this "behind the learning curve"
question:
I rarely need to provide CMYK files to clients so I
haven't noticed this before but when I do a conversion to U.S. Web Coated
Swop V.2 in Photoshop 7.0, it gives me a much different result than in 5.5.
In 7.0 the CMYK remains fairly close to the RGB ( except for absolute
colorimetric--which is drastic). Whenever I did a conversion in 5.5 I had
to do a lot of tweaking to the image because the conversion ( to the same
CMYK settings) always made it much darker, contrastier and with a color
shift.
David Kern
___________________________________________________________________________
Date: Sat, 22 Nov 2003 12:52:45 -0500
From: Lee Clawson
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Chris,
.... Because if it's a press, or anything that has less
than perfect
registration, yes we most likely want to discard
embedded profiles to avoid
automatic repurposing.
What is "automatic repurposing" ???
Lee
___________________________________________________________________________
Date: Sat, 22 Nov 2003 11:07:56 -0800
From: Doug Walker
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Friday, November 21, 2003, at 04:19 AM, Dan
Margulis wrote:
Shhh! Don't tell your color-management friends! Many of
them haven't realized
the drawbacks of wide-gamut RGBs just yet. What would
happen if they have to
surrender on this point too, after so many other
defeats?
Dan
Is this where a digital camera shots had no profile
associated with it, and so it was assumed?
Is there any connection to those of us using D1x who
CHOOSE Nikon Adobe RGB?
Thanks for clarification.
Doug Walker, FP
"Specializing in People on Location in a Clean,
Bold Classic Style!"
website: http://www.walkerphoto.com
Member, PPW, ASMP, APA SF
___________________________________________________________________________
Date: Sun, 23 Nov 2003 15:34:41 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Doug writes,
Is this where a digital camera shots had no profile
associated with it,
and so it was assumed? Is there any connection to those
of us using D1x who
CHOOSE Nikon Adobe RGB?
As I noted in the initial post, all I know is that the
images were shot digitally in a studio, and that we were presented with
CMYK files. Having seen the effect many times before, however, (and Chris
Murphy says the same thing) I surmised that the RGB files had been in Adobe
RGB and, whether in the initial exposure or in some subsequent RGB
correction, many objects wound up outside of the CMYK gamut.
If you're asking whether they just randomly assigned
Adobe RGB to images, I don't think so. If that were the case, everything
would have looked garish and dark. These images were basically OK except
when there were brilliantly colored objects.
There's definitely a connection to your work. In Adobe
RGB workflows for a CMYK destination, you have to be very watchful for
images that have critical objects that are out of the CMYK gamut. It's much
easier to have this problem in Adobe RGB than in the three other
"official" RGB definitions. If you send a file into CMYK
that's not colorful enough, it's easy to fix it in CMYK. If the file is so
colorful that all detail is wiped out during the transition, it'll take an
expert to make it look right afterward.
The solution when you identify such files is to apply a
false sRGB profile to them before converting into CMYK. That may make the
file look worse on your screen, but it will look *better* than the Adobe
RGB version even immediately after conversion. And if the client
isn't happy with the printed product he won't be interested in what the
file used to look like when it was in RGB.
Dan Margulis
___________________________________________________________________________
Date: Mon, 24 Nov 2003 10:11:57 -0700
From: Chris Murphy
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Nov 22, 2003, at 10:52 AM, Lee Clawson wrote:
What is "automatic repurposing" ???
A conversion intended to preserve the color appearance
of a file, by changing the numeric values in the file, that occurs without
prompting the user. It's effectively an automatic reseparation, or
automatic conversion.
I use the term automatic repurposing, because the color
is correct after such a conversion. From a theoretical point of view,
automatically repurposed files are exact what we need and want. But from a
practical view, printing presses have behavior that must be dealt with in
ways that conventional color management cannot handle (DeviceLinks can, to
a great degree do this, but they're rare and do not depend on embedded
profiles).
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Mon, 24 Nov 2003 10:21:23 -0700
From: Chris Murphy
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Nov 23, 2003, at 1:34 PM, Dan Margulis wrote:
There's definitely a connection to your work. In Adobe
RGB workflows for a
CMYK destination, you have to be very watchful for
images that have critical
objects that are out of the CMYK gamut. It's much
easier to have this problem in
Adobe RGB than in the three other "official"
RGB definitions. If you send a
file into CMYK that's not colorful enough, it's easy to
fix it in CMYK. If the
file is so colorful that all detail is wiped out during
the transition, it'll
take an expert to make it look right afterward.
If important detail hasn't been obliterated in the
process.
Perceptual rendering, in a case like this can be
helpful, as this is exactly what it is suited for. But because of the lack
of intelligent gamut mapping (it's a one size fits all thing), and
especially the profiles supplied by Adobe which have very similar rendering
intent behavior, this work around is only partial, and depends on the how
the profile was built.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Tue, 25 Nov 2003 08:28:45 -0000
From: Stephen Marsh
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Chris Murphy writes:
Perceptual rendering, in a case like this can be
helpful, as this is
exactly what it is suited for. But because of the lack
of intelligent
gamut mapping (it's a one size fits all thing), and
especially the
profiles supplied by Adobe which have very similar
rendering intent
behavior, this work around is only partial, and depends
on the how the
profile was built.
For those using SWOP TR001, Chromix also freely offer
to members a series of different GCR/UCR and ink weight at their
ProfileCentral site - but it has been down of late.
This has the same colorimetric data as the Adobe SWOP
profiles (when measuring AbsCol CMYK to LAB values) - but they do have more
'unique' behaviour than the more tame Adobe SWOP v2 profile.
Stephen Marsh.
___________________________________________________________________________
Date: Wed, 26 Nov 2003 11:24:21 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Chris Murphy writes,
Perceptual rendering, in a case like this can be
helpful, as this is
exactly what it is suited for. But because of the lack
of intelligent
gamut mapping (it's a one size fits all thing), and
especially the
profiles supplied by Adobe which have very similar
rendering intent
behavior, this work around is only partial, and depends
on the how the
profile was built.
Right. Separation algorithms have to compress the
amount of space allowed to colors that were out of gamut in RGB, otherwise
99.9 percent of all resulting pictures would look gray and rancid. The only
question is, how much. The relative colorimetric method that's now
recommended for most images basically answers, as much as possible. So, if
you have important OOG colors, this method is likely to hose them, but
other colors will be reproduced more accurately.
This "perceptual" idea is not to suppress OOG
contrast so much, at the price of somewhat flatter colors elsewhere. The
problem, as Chris indicates, is that there's no agreement on how much
"somewhat" means. In the Photoshop profiles, there's very little
difference, hence I don't even discuss it in classes because it wouldn't be
a problem to adjust a "RelCol" sep to match a
"Perceptual" one.
Profiles from other vendors might conceivably be a
different story, but even so, for this set of images we'd need something
really drastic, because these would be in the .1 percent of images where no
compression at all of the OOG colors might work. IOW, we'd have been better
off if the photographer had just opened up a blank CMYK document and pasted
the R,G,B into the C,M,Y, rather than try to convert from Adobe RGB through
any known CMYK profile. I guess we'd need something called
"Super-Perceptual" but there's not much chance of that.
The key here is to understand that it isn't a CMYK
problem or a separation algorithm problem. It's an RGB problem, where too
many critical areas of the image were, in Adobe RGB, way outside the CMYK
gamut. Adobe RGB users need to learn to recognize this narrow class of
images, and know how to bail out of Adobe RGB on them before making the
switchover.
Dan Margulis
___________________________________________________________________________
Date: Wed, 26 Nov 2003 12:11:46 -0700
From: Chris Murphy
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Nov 26, 2003, at 9:24 AM, Dan Margulis wrote:
This "perceptual" idea is not to suppress OOG
contrast so much, at the price
of somewhat flatter colors elsewhere. The problem, as
Chris indicates, is that
there's no agreement on how much "somewhat"
means.
And "somewhat" chances depending on the
colors in question, depending on the image itself, depending on the source
space, and the destination space, and what in the image is important and
what you're willing to sacrifice. This is so far beyond current color
management to handle that it would be like driving the space shuttle with
the steering column of a tricycle. It's just insufficient to the task (not
that it claims to be able to do it, but that's beside the point.)
Profiles from other vendors might conceivably be a
different story, but even
so, for this set of images we'd need something really
drastic, because these
would be in the .1 percent of images where no
compression at all of the OOG
colors might work. IOW, we'd have been better off if
the photographer had just
opened up a blank CMYK document and pasted the R,G,B
into the C,M,Y, rather than
try to convert from Adobe RGB through any known CMYK
profile. I guess we'd
need something called "Super-Perceptual" but
there's not much chance
of that.
My memory has failed me on the name of the product
acquired by Pictographics that had a kind of workaround for this. It was a
profile building application that allowed the user to select a source
space, and build an output profile's gamut compression contingent on that
source space. So you could build a profile that was geared to handle Adobe
RGB (1998) images - of course sacrificing somewhat its ability to render
from other sources.
Again this is still a one size fits all, in that the
same amount of gamut compression would apply to all Adobe RGB images (or
whatever the source space was when building the output profile) equally.
Current technology doesn't do image analysis to dynamically compress the
gamut. But this kind of workaround is certainly better than what we have
now, in my opinion, which involves a much broader assumption. And we know
what can happen when assumptions are made.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Sat, 29 Nov 2003 15:40:05 -0800
From: Doug Walker
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Friday, November 21, 2003, at 04:19 AM, Dan
Margulis wrote:
Shhh! Don't tell your color-management friends! Many of
them haven't realized
the drawbacks of wide-gamut RGBs just yet. What would
happen if they have to
surrender on this point too, after so many other
defeats?
Dan,
Would you mind expounding upon this just a bit more?
Is this what you refer to as an 'out of gamut' problem
for images where most of the critical image is out of gamut?
Doug Walker, FP
___________________________________________________________________________
Date: Tue, 2 Dec 2003 12:24:29 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Doug Walker writes,
Dan,
Would you mind expounding upon this just a bit more?
Is this what you refer to as an 'out of gamut' problem
for images where
most of the critical image is out of gamut?
While wider-gamut RGB definitions have certain
advantages, we have had a number of discussions of some of their drawbacks
in the last year or so. Without rehashing these totally, the basic problems
are, as you mentioned, devotion of too much space to colors that can't be
printed or in some cases even displayed correctly on the monitor; channels
that are excessively volatile in their effect on the image, making accurate
color correction difficult; and the necessity of monitoring what happens to
the file if it ever leaves your hands because a misinterpretation of a
wider-gamut RGB file by someone else is likely to be disastrous.
For these reasons, I personally feel that for a skilled
user, if the final destination of the file is CMYK, Adobe RGB is the
poorest choice of the four major RGBs. Beginners may get better results
with Adobe RGB, however, because it tends to create a more colorful result.
The remark that you quoted merely called attention to
the fact that most color management advocates, being sRGB-phobic, haven't
yet adopted this view, although in almost all other respects the
conventional color management wisdom has come around to occupying positions
I held more than five years ago.
Dan Margulis
___________________________________________________________________________
Date: Tue, 02 Dec 2003 15:00:15 -0500
From: Terry Wyse
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
on 12/2/03 12:24 PM, Dan Margulis wrote:
The remark that you quoted merely called attention to
the fact that most
color management advocates, being sRGB-phobic, haven't
yet adopted this view,
although in almost all other respects the conventional
color management wisdom has
come around to occupying positions I held more than
five years ago.
I think it's a matter of context. In the last 5-6 years
that I've been reading anything I can get my hands on about color
management and as a "practicing" color management
idiot/consultant for the last 3-4 years, I can't recall anybody advocating
wide-gamut RGB spaces to the exclusion of all others. It's ALWAYS been a
matter of choosing your RGB working space based on a
"capture-centric" viewpoint (keep ALL the original color data
because you NEVER KNOW when you might need it) versus an
"output-centric" view that sez "why keep all the extra
'color' if I'm never going to use it?". Both are right and have merit
in my view. The first knows that, going in, they won't get all that color
on output and furthermore don't have the ability to even SEE all the color
given the current state-of-the-art with displays. The second knows that,
while they have the "comfort" of working in a space that better
fits what they can print and display, they're losing a lot of flexibility
should different output options present themselves. Any "good"
color management consultant or savvy end-user should know this and either
understand their workflow or explain to their client what sorts of
compromises they will be making with EITHER approach. It's rarely a one
size-fits-all proposition when you're dealing with clients that range
anywhere from offset print production to digital photo studios to museums
capturing art. Personally, I think a case can be made for a 16-bit Lab
"digital master" (think of it as the transparency) that gets
archived and a production/working file that gets brought into something
like ColorMatchRGB (and, yes, even sRGB!) as an editing space in
preparation for CMYK output.
One example would be my current digital camera
"workflow" with my Sigma SD-9. When I started with this camera, I
would convert from RAW (X3F file) to Adobe RGB and had lot's of problems
with fleshtones. I'm now using ColorMatchRGB has my space of choice because
I feel I get better results. It could very well have to do with the fact
that ColorMatchRGB is a very good fit to my monitor's color space as
opposed to any notion of AdobeRGB being inferior in some way. The point is,
for my work with this camera (inkjet photo printing), ColorMatch gives me
what I'm looking for and is easy to work with. On the other hand, I'd like
to think monitors will get better and we'll have wider-gamut output choices
in the future, which is why, in my case, I ALWAYS save/archive the raw file
in case that happens. So I work in an "output-centric" mode but I
still keep one eye on the "capture-centric" view because, well,
you NEVER KNOW.... :-)
Cheers,
Terry
--
__________________________________
WyseConsul
Color Management Consulting
v 704.843.0858
__________________________________
___________________________________________________________________________
Date: Tue, 02 Dec 2003 22:29:41 +0000
From: Martin Orpen
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
on 2/12/03 8:08 pm, Dan Margulis wrote:
The remark that you quoted merely called attention to
the fact that most
color management advocates, being sRGB-phobic, haven't
yet adopted this view,
although in almost all other respects the conventional
color management wisdom
has come around to occupying positions I held more than
five years ago.
I think you have to distinguish between different types
of colour management advocates Dan :-)
Those of us that have to work with CMYK - films and
Cromalins and everything - are well aware of the problems of getting good
separations from *wider gamut* RGBs.
The maligned sRGB colour space might be small, but if
you want detail in red clothing and your model is looking a bit flushed
it's a hell of a lot better than AdobeRGB1998.
For anybody interested in reading more about this
stuff, we've been transferring (and updating) some examples from our old
web site to a new php-based site. One of the pages that was copied over
today is called "Why I hate 98" and can be reached via this link:
http:
//prometheus.idea-digital.com/phpbb2/viewtopic.php?t=61
You have to register to read it but there's plenty of
stuff there to make it worthwhile and we are copying more information over
on a daily basis :-)
--
Martin Orpen
Idea Digital Imaging Ltd -- The Image Specialists
http://www.idea-digital.com
___________________________________________________________________________
Date: Tue, 02 Dec 2003 16:25:05 -0700
From: Andrew Rodney
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
Cromalins ... Ugh.
I1ve produced more images using Adobe RGB (as have my
clients) to print then I can shake a stick at. There1s nothing inherently
dangerous about this space than any other space IF (big if) you know what
you1re doing and you use proper color management. Yes, the space is larger
than CMYK gamut but then sRGB (and even ColorMatch RGB) can1t fully contain
the CMYK gamut. IF getting full saturation cyan's and greens is important,
you1re going to have to find something larger than sRGB! In fact, most
capture devices are far wider than all the spaces so far discussed. Do you
really think the high end drum scanners of past where really unable to
capture wide(er) gamut than what they pushed out the back end? With the on
the fly conversions into CMYK, done correctly, no worries. Same with taking
Adobe RGB (or even a wider gamut RGB file) and converting. Upside is that
IF you ever need to go out to a wider gamut printer, you1ve got the
original data. That1s nice to have.
There1s no question that sRGB has gotten a bum rap.
Some make it sound as if you1re going to get pure junk if a file ends up in
this space. That1s simply as inaccurate as suggesting that a wide gamut RGB
space will produce junk in the right hands. Taking a file that isn1t Adobe
RGB and calling it that (or take a file that is Adobe RGB and tag it
differently) WILL produce really bad color. But a mistake is a mistake and
it1s not the cause of the colorspace.
Yes, there are some colors that fall outside Adobe RGB
that your display can1t show you (although NEC Mitsubishi Japan has
announced a 22" CRT monitor which is said can be calibrated to Adobe
RGB color space/gamut). Give the choice between funneling a file into a
space that insures I can't fully reproduce it on any number of devices
verses not seeing some areas on screen, I'll take the larger space. I like
to keep my options open.
There is absolutely no reason, given good conversions
from either space why one should produce better detail than the other. If
you're seeing flushed skintones, it's due to an incorrect assignment of the
numbers in the first place. Assign Adobe RGB to a file that's really sRGB
and you'll get butt ugly skin tones. But then that's a totally incorrect
way to handle the file so I don't see how Adobe RGB is at fault.
FYI, Adobe didn't invent Adobe RGB (at least not on
purpose). Those who recall a space called SMPTE-240m in the original 5.0
version of Photoshop should know that it soon after got renamed to Adobe
RGB when SMPTE informed Adobe that two of the chromaticity values they
themselves placed on their website specifying this space were incorrect!
Fortunately much testing proved (and continues today to prove) that the mix
up produced a well behaved editing space none the less. In the following
dot release, Adobe had no choice but to rename the space since it wasn't
really SMPTE-240m.
It might be politically popular to call either Adobe
RGB (or elsewhere sRGB) bad spaces but the facts are, there are no perfect
Working Spaces. All the working spaces will produce really ugly final
output if handled incorrectly. What we want is a space that can at the very
least contain all the colors we hope to eventually reproduce.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Wed, 03 Dec 2003 00:30:03 +0000
From: Martin Orpen
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
on 2/12/03 11:25 pm, Andrew Rodney wrote:
I1ve produced more images using Adobe RGB (as have my
clients) to print then
I can shake a stick at. There1s nothing inherently
dangerous about this
space than any other space IF (big if) you know what
you1re doing and you
use proper color management. Yes, the space is larger
than CMYK gamut but
then sRGB (and even ColorMatch RGB) can1t fully contain
the CMYK gamut. IF
getting full saturation cyan's and greens is important,
you1re going to have
to find something larger than sRGB!
You'll note that my beef with AdobeRGB1998 is with reds
- not cyan and green. And because we deal with images the sometimes have
people in them, this is a rather important bit of the colour spectrum for
us.
Nobody's that bothered if the grass is a bit of an odd
colour - a supermodel with sunburn is a different matter.
In fact, most capture devices are far
wider than all the spaces so far discussed. Do you
really think the high end
drum scanners of past where really unable to capture
wide(er) gamut than
what they pushed out the back end? With the on the fly
conversions into
CMYK, done correctly, no worries. Same with taking
Adobe RGB (or even a
wider gamut RGB file) and converting. Upside is that IF
you ever need to go
out to a wider gamut printer, you1ve got the original
data. That1s nice to
have.
We've got the benefit of still having high-end drum
scanners right here in the studio. And like the true *calibrationists* that
we are, we make our own profiles with *monster-sized* gamuts.
But my problems with AdobeRGB1998 arise from images
that are supplied to us - not those that we create (with the exception of
negatives which are another good reason to avoid wide gamut RGB spaces -
but that's another story).
There1s no question that sRGB has gotten a bum rap.
Some make it sound as if
you1re going to get pure junk if a file ends up in this
space. That1s simply
as inaccurate as suggesting that a wide gamut RGB space
will produce junk in
the right hands. Taking a file that isn1t Adobe RGB and
calling it that (or
take a file that is Adobe RGB and tag it differently)
WILL produce really
bad color. But a mistake is a mistake and it1s not the
cause of the
colorspace.
This may be true.
But for the sake of argument I'd be willing to state
that you are more likely to get a better result from sRGB to CMYK than from
AdobeRGB1998 to CMYK from a bunch of randomly selected untagged RGB
originals.
It's far easier to saturate and add contrast than it is
to try and rescue detail from solid areas.
There is absolutely no reason, given good conversions
from either space why
one should produce better detail than the other. If
you're seeing flushed
skintones, it's due to an incorrect assignment of the
numbers in the first
place. Assign Adobe RGB to a file that's really sRGB
and you'll get butt
ugly skin tones. But then that's a totally incorrect
way to handle the file
so I don't see how Adobe RGB is at fault.
It's at fault because it's so difficult to make the
judgement from the screen rendition that you've pushed the reds too far.
Few of my clients are watching the numbers and more often than not the skin
tones and detail in reds suffer.
What you say is true - but you're having to make too
many provisos: "given good conversions"; "if you know what
you're doing"; "using proper colour management" etc.
This stuff goes out the window on a Friday afternoon
when the ad deadlines are looming and we've got no control over the images
that are supplied to us.
It might be politically popular to call either Adobe
RGB (or elsewhere sRGB)
bad spaces but the facts are, there are no perfect
Working Spaces. All the
working spaces will produce really ugly final output if
handled incorrectly.
What we want is a space that can at the very least
contain all the colors we
hope to eventually reproduce.
So what RGB space would you suggest for people who are
producing images that will be primarily reproduced in European magazines?
(and what CMYK space for that matter? - Photoshop seems to be sadly lacking
in both areas.)
--
Martin Orpen
Idea Digital Imaging Ltd -- The Image Specialists
http://www.idea-digital.com
___________________________________________________________________________
Date: Tue, 2 Dec 2003 17:59:53 -0700
From: Chris Murphy
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Considering that the problem has only been talked about
in earnest for the past year, and that vastly more people have a fine and
dandy experience with Adobe RGB (1998) than they have problems with it, I
still think it is a good editing space to use. That one needs to be
vigilant with respect to high saturation areas with fine detail is really
not anything new, just that we have a more recent reminder that this
problem becomes increasingly greater the larger the editing space gamut is.
But I do agree that wide gamut RGB spaces are
recommended more often by those using color management. This makes sense.
These people can take advantage of such wider gamut spaces, despite the
possibility of getting bitten every now and then. That there was also a big
rush to negatively judge sRGB I don't think is in dispute either. From a
traditional print perspective, it's unlikely that sRGB is really going to
negatively impact your work and by design Photoshop still has the ability
to show you what you're going to get (or not get) if sRGB is your editing
space.
There is clear value in wide gamut RGB spaces. NEC has
a monitor available in the Japanese market that has Adobe RGB (1998)
primaries. It stands to reason that as output devices increasingly have
wider gamuts, that our displays will need to have them also. The problem,
as I see it, is that the industry is finding color management as it exists
today to be unsophisticated enough. It's conversions are good, but they're
not at all intelligent. The conversions allow the potential for serious
damage to occur in the course of conversion, by way of important detail
being dropped. There are both short term and long term work arounds for
this problem, but I don't really see the industry moving toward either at
this point.
Anyone worked with e-sRGB yet? There's a whacky fun
color space.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Tue, 02 Dec 2003 18:57:56 -0700
From: Andrew Rodney
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
on 12/2/03 5:30 PM, Martin Orpen wrote:
You'll note that my beef with AdobeRGB1998 is with reds
- not cyan and
green. And because we deal with images the sometimes
have people in them,
this is a rather important bit of the colour spectrum
for us.
You1re missing the point. Cyans and Green1s fall
outside CMYK gamut in a smaller space. There should be NO reason why you1d
have ANY problem with reds.
Nobody's that bothered if the grass is a bit of an odd
colour - a supermodel
with sunburn is a different matter.
If the file is handled correctly, the reds will
reproduce just fine in Adobe RGB as they did in sRGB (unless you have reds
that were out of gamut then you might actually be able to fit them into the
smaller space). Take your file in Adobe RGB and sRGB and if handled
correctly, upon conversion they will have the same color appearance.
We've got the benefit of still having high-end drum
scanners right here in
the studio. And like the true *calibrationists* that we
are, we make our own
profiles with *monster-sized* gamuts.
So you've got monster sized RGB files bigger than Adobe
RGB. No problem right?
But my problems with AdobeRGB1998 arise from images
that are supplied to us
- not those that we create (with the exception of
negatives which are
another good reason to avoid wide gamut RGB spaces -
but that's another
story).
Because they are probably NOT in Adobe RGB and that's
my point. Just calling a file Adobe RGB doesn't make it such. And this
might be Dan's point but I don't agree that poor work habits are the fault
of anyone but the person who hosed the file. It's not the fault of Adobe or
Adobe RGB. IF I give you a file that really is sRGB and tell you it's Adobe
RGB by virtue of the tag, the file will output poorly and that's no reason
to say sRGB is at fault. It's user error.
This may be true.
It really is <g>
But for the sake of argument I'd be willing to state
that you are more
likely to get a better result from sRGB to CMYK than
from AdobeRGB1998 to
CMYK from a bunch of randomly selected untagged RGB
originals.
No, I don't buy that. You'll clip colors. If what
you're saying is, we should dumb down all this stuff to the lowest common
dominator and use sRGB due to this, I don't buy that. I'd rather have all
the colors I can possibly produce. I think some here do a disservice by
dumbing down the process rather than teach good work habits. Untagged RGB
is just BAD! It's not acceptable.
It's at fault because it's so difficult to make the
judgement from the
screen rendition that you've pushed the reds too far.
Few of my clients are
watching the numbers and more often than not the skin
tones and detail in
reds suffer.
Numbers without meaning are useless. That's why we have
profiles. I can provide you a dozen different numbers for the same
appearing RGB solid color all based on the colorspace. You know this. If I
give you an untagged file, the numbers are totally useless.
What you say is true - but you're having to make too
many provisos: "given
good conversions"; "if you know what you're
doing"; "using proper colour
management" etc.
Look, if you don't have good conversions, you don't get
good color. If you can't take the heat...
This stuff goes out the window on a Friday afternoon
when the ad deadlines
are looming and we've got no control over the images
that are supplied to
us.
Open the file, look at it on a calibrated display. If
the image looks good with the supplied profile, you're going to be fine at
this point and now you need a good output profile. Reds look way off? File
is untagged? What you're seeing (and the meaning of the numbers) are
suspect. You either fix the issue now or you get bad output. That's not the
fault of a colorspace. The wrong colorspace is being used to describe the
numbers.
So what RGB space would you suggest for people who are
producing images that
will be primarily reproduced in European magazines?
(and what CMYK space for
that matter? - Photoshop seems to be sadly lacking in
both areas.)
If you have clueless users, I'd pick ColorMatch before
sRGB but that's again lowering the standards to accommodate bad work
habits.
If all the "standard" RGB Working Spaces we
find in Photoshop, I'd pick Adobe RGB for print work because it's not that
much larger than the display and it fully contains the CMYK output gamut.
So you get all the colors you can possibly print (to this but not all other
devices) and it's not so huge you will be unable to see a lot of colors or
need a high bit file for editing (larger gamut editing spaces are more
appropriate to edit in more than 8 bits per color).
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Tue, 2 Dec 2003 19:49:23 -0800 (PST)
From: pictureelements
Subject: RGB CMYK conversion
Is there a document for the source code of both RGB
CMYK equations. How Photoshop convert RGB to CMYK and how Photoshop extract
the black from CMY is the goal.
Thank you
Steven Scott ASA
___________________________________________________________________________
Date: Tue, 02 Dec 2003 20:58:16 -0800
From: Kevin Connery
Subject: RGB Numbers (round 3) (was Re: Photoshop CS
defaults)
Martin Orpen wrote:
I think you have to distinguish between different types
of colour
management
advocates Dan :-)
And different focus as well.
Many of the photographers I work with rarely go to a
'real' CMYK printer; they're either printing on inkjects (2200/7600/9600
Epsons), or RGB printers (Frontiers/LightJets/Lambdas). In those
circumstances, much of what might be The Right View for CMYK-centric
workers may well not be optimum for them.
I often recommend sRGB to photographers who are new to
digital; it's safer, if potentially limiting. But I always point out that
they need to do their own testing to see if what they are shooting, and how
they are printing, is giving them what they want. If it's not, and the
limits are in the out of sRGB gamut areas, trying other spaces, Adobe RGB
in particular, may be better suited for their needs. If it IS working--and
it does to a LOT of professional photographers--there's little reason to
switch. Commercial photographers tend to be less happy with sRGB than
portrait/wedding folks, for a variety of reasons, and they're usually the
ones going to CMYK anyhow, which is a closer match to sRGB than Adobe RGB,
which is the most common alternative.
That has a lot more to do with proper capture and
editing techniques than anything else. A capture that can't hold the
essential colors/tones because it's going to too small a color space is
hard to truly fix, just as one that's going to use too little of the space
being used. WITH PROPER EDITING, getting good output from a too large space
is usually much easier than the reverse. With bad editing, it hardly
matters; the user's going to get lousy output.
Kevin Connery
___________________________________________________________________________
Date: Wed, 3 Dec 2003 13:25:34 -0000
From: Bob Frost
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
Martin,
Doesn't soft-proofing in PS take care of this?
Bob Frost
From: Martin Orpen
It's at fault because it's so difficult to make the
judgement from the
screen rendition that you've pushed the reds too far.
Few of my clients are
watching the numbers and more often than not the skin
tones and detail in
reds suffer.
___________________________________________________________________________
Date: Wed, 3 Dec 2003 09:47:44 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Terry Wyse writes, with somewhat similar sentiments
being expressed by Chris Murphy, Martin Orpen, and Andrew Rodney,
It's ALWAYS been a matter of choosing your RGB working
space
based on a "capture-centric" viewpoint (keep
ALL the original color data
because you NEVER KNOW when you might need it) versus
an "output-centric"
view that sez "why keep all the extra 'color' if
I'm never going to use
it?". Both are right and have merit in my view.
The first knows that, going
in, they won't get all that color on output and
furthermore don't have the
ability to even SEE all the color given the current
state-of-the-art with
displays. The second knows that, while they have the
"comfort" of working in
a space that better fits what they can print and
display, they're losing a
lot of flexibility should different output options
present themselves. Any
"good" color management consultant or savvy
end-user should know this and
either understand their workflow or explain to their
client what sorts of
compromises they will be making with EITHER approach.
Well, we seem to be one happy family then. There are
pluses and minuses that are going to affect each user differently. The way
I see it, the more important CMYK output is to you, the less attractive
Adobe RGB is. Also, the more likely it is that somebody other than yourself
is eventually going to handle the files, the less happy the Adobe RGB
scenario is. And vice versa in both cases.
But Terry adds (not necessarily with the support of the
others),
I think it's a matter of context. In the last 5-6 years
that I've been
reading anything I can get my hands on about color
management and as a
"practicing" color management
idiot/consultant for the last 3-4 years, I
can't recall anybody advocating wide-gamut RGB spaces
to the exclusion of
all others.
Then you have a short memory. Up until perhaps 18
months ago, anyone who had the temerity to suggest that sRGB might even be
a *workable* alternative for a professional--let alone possibly better than
Adobe RGB--would have been subject to great scorn and derision from
your colleagues. sRGB was called sickRGB, sadRGB, stupidRGB,
stinkoRGB, and, more commonly, a variant of the above that will not be
named here. At the time of Photoshop 5, one of Chris's co-authors
derided sRGB as being completely unusable in a professional context.
(I said it too at at the time, but recanted quickly). An Adobe
programmer said that anyone who used sRGB either was going to the Web or
didn't know what he was
doing.
Yesterday I received an e-mail from a list member
saying that, roughly one year ago, he attended a seminar taught by a
prominent Adobe shill who described sRGB as "Satanic RGB" and
ridiculed a user thereof. And only a few days more than a year ago, right
here on this list, Andrew ridiculed me for having the temerity to say that
the color management community was starting to realize that there were
problems with wide-gamut definitions as well as benefits.
Five years ago, a number of "experts" thought
that even Adobe RGB wasn't wide-gamut enough and that something even more
colorful was necessary. While that view isn't dead, many fewer people hold
it now, so I think it's fair to call it an idea whose time has come and
gone.
This is all, however, water under the bridge. Of the
comments posted yesterday, I agree most closely with Martin's position. But
I do think that what Andrew, Chris, and Terry are saying is reasonable and
gives the user enough information to make a sensible decision. That's
a welcome change from a few years back.
Dan Margulis
___________________________________________________________________________
Date: Wed, 03 Dec 2003 08:50:46 -0700
From: Andrew Rodney
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
on 12/3/03 6:25 AM, Bob Frost wrote:
Doesn't soft-proofing in PS take care of this?
No reason why it shouldn't.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
___________________________________________________________________________
Date: Wed, 03 Dec 2003 08:48:17 -0700
From: Andrew Rodney
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
on 12/3/03 7:47 AM, Dan Margulis wrote:
The way I see it, the more
important CMYK output is to you, the less attractive
Adobe RGB is.
There1s no reason this has to be other than user
ignorance. If you take a file in Adobe RGB, convert a COPY to sRGB and then
take both files and convert to CMYK you get the same CMYK numbers. At least
with the original file, you have the gamut to use for other output needs.
Also, the more likely it is that somebody other than
yourself is eventually
going to handle the
files, the less happy the Adobe RGB scenario is. And
vice versa in both cases.
Only if the user screws up, the originator doesn1t tag
the file (and we play the guessing game).
Up until perhaps 18 months ago, anyone who had
the temerity to suggest that sRGB might even be a
*workable* alternative for
a professional--let alone possibly better than Adobe
RGB--would have been
subject to great scorn and derision from your
colleagues.
By and large, I1d agree that it1s a silly thing to do
and sRGB is not better. To reduce the possible colors you can output to
something as small gamut as CMYK ink on paper (and ignoring all the other
output devices who1s gamut exceeds it), is just silly since both
colorspaces when properly used will NOT produce ugly output (but one will
produce a wider gamut from the device).
Yesterday I received an e-mail from a list member
saying that, roughly one
year ago, he attended a seminar taught by a prominent
Adobe shill who
described sRGB as "Satanic RGB" and ridiculed
a user thereof. And only a few days more than a year ago, right here on
this list, Andrew ridiculed me for having the
temerity to say that the color management community was
starting to realize
that there were problems with wide-gamut definitions as
well as benefits.
I1ve ridiculed you for being closed minded, for
promoting an inferior workflow because someone might be too stupid to use
the tools correctly and completely ignoring any output use other than what
you know and love (CMYK ink on paper). There1s no problem with wide gamut
spaces WHEN USED PROPERLY. There1s no problem with Alpha channels unless of
course you don1t know that the RIP you1re sending the file to will have a
hissy fit if one is included. Or that taking a file and saving a JPEG at
quality level 2 and throwing away the original might produce some real
issues when it1s output at twice the size it was originally scanned at. Or
that putting your car1s transmission in 3R2 and slamming on the gas petal
might arrearage your garage. I don1t see anyone here slamming people for
doing anything really silly with color unless it comes to some colorspace
(which many here totally ignored when Photoshop 5 came out and introduced).
To suggest that sRGB is a safer, better space because
some users haven1t a clue what a colorspace is, how to embed a profile or
how to carry out a conversion is simply irresponsible from people who1s aim
is to educate users on proper digital workflow!
Five years ago, a number of "experts" thought
that even Adobe RGB wasn't
wide-gamut enough and that something even more colorful
was necessary. While
that view isn't dead, many fewer people hold it now, so
I think it's fair to call
it an idea whose time has come and gone.
And it1s NOT wide enough for SOME output needs. If
you1d only stop thinking about CMYK as your only reality. The world doesn1t
revolve around a CMYK printing press. Adobe didn1t produce Photoshop for
Dan1s color theory exercises. There are people working in all kinds of
media using color, Photoshop and imaging that simply can1t produce
acceptable output with sRGB let alone other wider gamut spaces. But this is
3CMYK Color Theory2 not really 3Color Theory2 right?
This is all, however, water under the bridge. Of the
comments posted
yesterday, I agree most closely with Martin's position.
But I do think that
what Andrew, Chris, and Terry are saying is reasonable
and gives the user enough
information to make a sensible decision. That's a
welcome change from a few
years back.
I can1t speak for Terry but that1s all Chris, Bruce
Fraser (and yes, it1s in PRINT from PS 5 days) and I have said for years.
Adobe RGB doesn1t kill files, people kill files!
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Wed, 03 Dec 2003 10:35:15 -0800
From: Steven Barton
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
Andrew Rodney wrote,
To reduce the possible colors you can output to
something as small
gamut as CMYK ink on paper (and ignoring all the other
output devices who1s
gamut exceeds it), is just silly since both colorspaces
when properly used
will NOT produce ugly output . . .
If a digital photographer is providing photos to be
used in print advertising, it is very unlikely that these images would ever
be used on any larger-gamut device. In most cases, these same images might
be repurposed for use on a web site, but in that case they would usually be
prepared in sRGB, I believe. So when the photographer sets contrast for the
images, what real benefit would there be in setting the contrast in a
wide-gamut color space, when the primary purpose of the images is for
commercial CMYK printing? Why expand the color range only to compress it
again and invite errors in translation?
Or, if the client is present at the photo shoot and is
approving the images on-screen, why misrepresent the intended result by
producing shockingly rich color on-screen that cannot possibly be
reproduced on a commercial printing press running to industry standards?
Steven Barton
Imaging Sciences & Partners LLC
___________________________________________________________________________
Date: Wed, 3 Dec 2003 18:03:22 -0000
From: Bob Frost
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Dan,
I'm no "expert", but even I know that Adobe98
is not large enough to capture all the colors that might be in a film scan
or digital capture. That is why people produced larger spaces - EktaSpace
to contain what might be in Ektachrome, BestRGB to add in what might also
be in Velvia, ProPhotoRGB to contain what might be in almost anything! So
it makes sense to me (a former scientist) to use a working space that will
contain any colors that I send to it.
I fully understand that I won't be able to see all
those colors on my current monitors, or print them on my current printer,
and that I will need to use softproofing with good custom profiles to
finalise my images, but that is no reason for throwing away those colors
that are in the real world and on film and in camera output.
Who knows what the gamut of our printers will be in
10-20 yrs time? Will we even be looking at images printed on paper?
Already, NEC have a monitor with Adobe98 gamut, not sRGB or AppleRGB or
Colormatch. My Epson printers print colors outside sRGB or Colomatch, so
why would I want to throw these away by using such a small working space.
Just because some people do not understand color
management, or are just averse to change and do not want to understand
color management, does not mean that it is nonsense and that people who do
use it should be ridiculed so often as you seem to do.
Just remember what happened to the dinosaurs; the world
changed, and they wouldn't or couldn't.
Bob Frost.
___________________________________________________________________________
Date: Wed, 03 Dec 2003 18:43:28 +0000
From: Martin Orpen
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Dan Margulis wrote:
This is all, however, water under the bridge. Of the
comments posted
yesterday, I agree most closely with Martin's position.
But I do think that
what Andrew, Chris, and Terry are saying is reasonable
and gives the user enough
information to make a sensible decision. That's a
welcome change from a few
years back.
Which is the important thing - giving the user enough
information so that they can make their own decision.
The reason I posted here (and made a related post to
CSUG) is that AdobeRGB1998 and the Euroscale v2 profiles are a combination
that I distrust.
They are also the recommended options from Adobe for
European pre-press work.
Adobe's working RGB space seems (to me) to be an easy
space in which you can make big mistakes with reds and skin tones.
Euroscale v2 produces separations (to my eye) that are blue biased and open
in shadows.
The two profiles appear to complement each other - but
this isn't what profiles are supposed to do :-(
If you go from AdobeRGB to high quality European CMYK
profiles like ISOcoatedsb, you get a result that is too warm and a little
clogged in the shadows. This shouldn't happen because Euroscale v2 is
supposed to be based on the same results that were used to create the
ISOcoatedsb profile.
And don't get me started on Photoshop's custom CMYK
profiles...
People using Photoshop to create images for European
magazines have a very limited set of tools - no usable CMYK profile
certainly. It shouldn't be that way.
Regards
--
Martin Orpen
Idea Digital Imaging Ltd -- The Image Specialists
http://www.idea-digital.com
___________________________________________________________________________
Date: Wed, 3 Dec 2003 12:07:23 -0800 (PST)
From: pictureelements
Subject: Re: RGB CMYK conversion
Hi all members of this group,
I just want to add that the basic conversion find is
Black =
minimum(1-Red,1-Green,1-Blue)
Cyan =
(1-Red-Black)/(1-Black)
Magenta = (1-Green-Black)/(1-Black)
Yellow =
(1-Blue-Black)/(1-Black)
However, the result does not match Photoshop. All of
the resources found for color conversions are fairly superficial and give
only theoretical math. We have yet to find any reference that discusses the
conversion in real depth or acknowledges the difference with Photoshop. Any
idea?
Thank you
Steven Scott ASA
___________________________________________________________________________
Date: Wed, 03 Dec 2003 16:49:29 -0800
From: "Jeff Smith"
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
Steven Barton wrote:
If a digital photographer is providing photos to be
used in print
advertising, it is very unlikely that these images
would ever be used on any
larger-gamut device.
In the world I work in as a commercial photographer
specializing in print work, our digital work is quite often output to
devices other than the ink-on paper CMYK. Repurposing images for trade show
booth use, POP and instore display use is fairly common. Output to Lambda
prints or high-end, one-off injets for display work is pretty common.
Or, if the client is present at the photo shoot and is
approving the images
on-screen, why misrepresent the intended result by
producing shockingly rich
color on-screen that cannot possibly be reproduced on a
commercial printing
press running to industry standards?
Depends on the client. Most of our clients for high-end
print work are very familiar with the compromises that need to be made when
going to press. They also like to know that they are starting with a
full depth original that can stand up to the pressures of being converted
ultimately to CMYK for the press. When we shot large format transparency
film, clients saw lots of color that was not reproducable. They're big
people - they can accept the trade-offs of various reproduction methods a
lot better than some of us care to appreciate. They also come to appreciate
the craft (as practiced through careful imaging, adept prepress and
fastidious press work) of wringing as much color as possible out of ink on
paper.
--
Jeff Smith
Smith/Walker Design and Photography
P. O. Box 58630
Seattle, WA 98138
ph: 206-575-3233
___________________________________________________________________________
Date: Wed, 3 Dec 2003 08:44:50 -0800
From: Pat Sagers
Subject: RE: Re: Photoshop CS defaults, was: RGB
Numbers (ro und 2)
Got a quick question. If I depend on my monitor
for and paper/printer profiles to "proof" my images. How do
I depend on the numbers. Won't they be different. Let's say I
have an RGB value that looks very different on every device/paper. Is
there a way to get it right by the numbers and then depend on the profiles
to do the right thing when sent to a paper/printer
combination?
Thanks
Pat
___________________________________________________________________________
Date: Wed, 03 Dec 2003 18:07:58 -0700
From: Andrew Rodney
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
on 12/3/03 11:35 AM, Steven Barton wrote:
If a digital photographer is providing photos to be
used in print
advertising, it is very unlikely that these images
would ever be used on any
larger-gamut device.
As someone that spent a decade shooting for a living
and a good decade working with photographers digitally, that1s not at all
accurate!
Photographers don1t sell actual images, but rather
rights to images and those images can and are reproduced all over the world
off all kinds of devices. To suggest that photographers simply limit the
use of their images for ink on paper only is very short sighted.
I1m still today selling images of the 1984 LA Olympics
I shot way back then (on of all things film). The usages are all over the
map.
Or, if the client is present at the photo shoot and is
approving the images
on-screen, why misrepresent the intended result by
producing shockingly rich
color on-screen that cannot possibly be reproduced on a
commercial printing
press running to industry standards?
I1d NEVER show an Art Director the image in a Working
Space, only an output space (because I1ve worked with them long enough to
know that they will expect that on output and that1s impossible). Luckily
we have really good soft proofing in Photoshop and I can keep the high
gamut original for any possible need I might have while showing the AD what
the image will look like ink on paper.
To funnel a file into a smaller gamut is like ignoring
history and painting yourself into a corner. I1ve said that now more than
once, no reason to say so again. I have yet to hear any compelling argument
as to why I should limit the possibilities of my images simply to assist
someone down the line who may have no clue about handling images and has no
right to be handling images.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Wed, 3 Dec 2003 20:37:08 -0700
From: Ron Kelly
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Andrew:
Slip of the tongue, perhaps, perhaps not.
What's "proper" smacks of a moral judgment;
let's not go there. Understanding the issues good, pronouncing one option
(yours) "the correct way" bad.
Ron Kelly
___________________________________________________________________________
Date: Wed, 03 Dec 2003 19:52:19 -0700
From: Andrew Rodney
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (ro und 2)
on 12/3/03 9:44 AM, Pat Sagers wrote:
Got a quick question. If I depend on my monitor
for and paper/printer
profiles to "proof" my images. How do I
depend on the numbers.
You can1t to a very large degree. One beauty of RGB
Working Spaces is that they are well behaved in so much that when R=G=B,
you have a neutral. That you can depend on. That is not the case with all
(or in fact many) input and output spaces (be it RGB or CMYK).
RGB and CMYK are device dependant colorspaces. That
means any number of RGB (or CMYK) numbers can produce the same color
appearance. Or to put it another way, you might need vastly different sets
of numbers to produce the same color on different devices.
Let's say I have an RGB value that looks very different
on
every device/paper. Is there a way to get it
right by the numbers and then
depend on the profiles to do the right thing when sent
to a paper/printer
combination?
The profile tells us the meaning of the numbers.
Numbers do NOT tell us what a color looks like. It1s only an ingredient for
the color. Numbers with profiles can produce correct color appearance on
screen (and insure the correct numbers produce the color on output). If
you1re talking about an RGB Working Space, equal values are neutral. We
also know that zero is as black as we can get and 255 is as white as we can
get. But we don1t necessarily know what value near zero or 255 produces the
next reproducible value on output (since again, output spaces are device
dependant).
Working by the numbers has been greatly over rated for
those who have to work with many output devices. If you spend years working
with the same device, you can become familiar with the values that will for
example produce a good skin tone. But take that known set of numbers and
send to another device and all bets are off. If you work in a tightly
controlled environment and send known numbers to the same device day in and
day out, you can rely on those numbers. But in today1s world where we have
so many different devices (and substrates, just look at all the papers you
can run through an Ink Jet printer), you can1t rely on specific numbers
very long.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Thu, 04 Dec 2003 08:21:11 -0000
From: Stephen Marsh
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(ro und 2)
There are various degrees to working by the numbers -
this is a rather broad term to my way of thinking. I use by the numbers
methods and soft-proofing - taking advantage of both. By the numbers could
be something as simplistic as ensuring that pure white/black is correct,
and or shadow and highlights and or neutrals - in RGB or CMYK. Going a
little deeper, it could be evaluating and editing a skintone with a certain
ratio of C to M to Y (or R to G to B), not shooting for a specific target
colour, but a general relationship that is known to be pleasing in a
certain setting, using both the ratios of values and the soft-proof view.
Or it could be that I am altering colour to a specific target colour mix
that is known to be the required hue - without any care of the soft-proof.
Remember the recent posts on illusions - colour depends
on context and your numbers may need to be altered, which demonstrates that
numbers only go so far, just as soft-proofing only goes so far. The
contextually adaptive nature of human vision plays a big part in all of
this.
A particular CMYK space that is used as a working space
and becomes intimately familiar - is not that different to a RGB working
space...in that they are both sets of numbers which take on a specific
meaning when coupled with a description (table, profile or whatever). So in
theory one could become just as familiar with ratios and balances of RGB,
just as in a flavour of CMYK - or perhaps even get to intimately predict
more accurate targeted colour mixes.
My basic point is that it does not matter if you are
comfortable with a certain flavour of RGB or CMYK - this value can be read
as a LAB value, which can then be used in any other mode and flavour in
Photoshop (apart from out of gamut issues). RGB or CMYK does not matter,
all that matters is that you know how a certain mix of values behaves when
transformed from source to destination.
There are other options - one can use device
independent LAB values, if you could work by the numbers in LAB info
readings while in RGB then you have a formula that is not tied to a
particular space. When mixing values by hand in different RGB, use the LAB
aim-point (as the RGB build no longer makes sense). Some Pantone books use
LAB, which is a good example.
Numbers and profiles do not have to be mutually
exclusive - one can take advantage of both methods.
Stephen Marsh.
___________________________________________________________________________
Date: Thu, 4 Dec 2003 09:24:30 EST
From: Dan Margulis
Subject: Re: RGB CMYK conversion
Steven Scott writes,
I just want to add that the basic conversion find is
Black =
minimum(1-Red,1-Green,1-Blue)
Cyan =
(1-Red-Black)/(1-Black)
Magenta = (1-Green-Black)/(1-Black)
Yellow = (1-Blue-Black)/(1-Black)
However, the result does not match Photoshop.
Nor should it. This is the way separations were made by
process cameras. The digital age offers so much more sophistication that
you're looking for an answer to a question that doesn't have one. A
Photoshop separation will have something in common with the above formula,
yes, but it's really governed by two different matrices or profiles, one
for RGB and one for CMYK, each of which in effect creates one of two
monstrous look-up tables that work together in tandem. So, the only way you
can get a specific formula is by choosing one specific RGB profile and one
specific CMYK profile, and even then the exact technical description of
what was going on could be quite lengthy, as in, more than a megabyte.
The *basic* problems--which are by no means the only
ones--are:
*In RGB, all color values are unique, but in CMYK there
are typically many different ways of constructing the same color.
*The above formula assumes that cyan ink absorbs red
light totally, which it doesn't do in the real world; but even if it did
the blueness of cyan ink varies from region to region--the North American
version of cyan is greener than that customarily found in Europe.
*The above formula assumes that magenta is the direct
opponent of green, but in fact all magenta inks favor red somewhat;
further, because the magenta ink is often made even redder by contamination
on press some profiles are designed to cater to the possibility because a
lot of people really dislike beet-red fleshtones.
*Whenever there's a serious mismatch between the gamuts
of the two spaces there isn't going to be any one right way of handling the
problem. CMYK doesn't handle bright blues or pastel colors well and RGB
doesn't have a good yellow. Any method one chooses to deal with these
facts of life will be correct at certain times and incorrect at others.
Dan Margulis
___________________________________________________________________________
Date: Thu, 04 Dec 2003 17:54:13 -0000
From: "Scott Larsen"
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Andrew Rodney wrote:
If you'd only stop thinking
about CMYK as your only reality. The world doesn't
revolve around a CMYK
printing press. Adobe didn't produce Photoshop for
Dan's color theory
exercises. There are people working in all kinds of
media using color,
Photoshop and imaging that simply can1t produce
acceptable output with sRGB
let alone other wider gamut spaces. But this is
"CMYK Color Theory" not
really "Color Theory" right?
Works for me. ;-)
I'm not against knowing what to do in all cases, but
the fact is that more than 99% of the images I work with will be CMYK.
Should I expend significant time and energy and storage space on wide-gamut
versions of my scans "just in case" something changes in a
decade? No. My company does have a website, and does occasionally produce
inkjet prints, so I do need to know how to handle these, but my bread and
butter is CMYK and if a particular scenario is promoted as best for CMYK at
the expense of other output possibilities, I'll still opt for it.
I've posted here a couple of times, but might want to
jump into the fray a little more often, so here's my introduction:
I spend a few minutes a day with Dan's book, comparing
it with what I read here, and trying to try new techniques in my everyday
workflow. I learn a lot from this list but still am learning who's who and
what your histories are. In 2001 I attended the GATF Color Management
seminar in Phoenix. Out of the hundreds of attendees, I was the only one
from the design side of a publication. Here's a page from one of the
sessions' PowerPoint show:
" Working Space Guidelines:
Use Adobe RGB (1998) for print and
non-print work.
Use ColorMatch RGB for newspaper
applications.
Use sRGB for Internet imaging
Use Customized Adobe Working
Spaces"
Couple this with the fact that I took a hiatus from
printing (owned a coffeehouse for a while) and skipped from Photoshop 4 to
6, you can see that I am thoroughly messed up. So thanks for this forum,
and your understanding.
-Scott Larsen
___________________________________________________________________________
Date: Thu, 04 Dec 2003 09:51:40 -0800
From: Steven Barton
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
Jeff Smith wrote:
In the world I work in as a commercial photographer
specializing in
print work, our digital work is quite often output to
devices other than
the ink-on paper CMYK. Repurposing images for trade
show booth use, POP
and instore display use is fairly common. Output to
Lambda prints or
high-end, one-off injets for display work is pretty
common.
Thank you for your valuable perspective. It brings to
mind one other issue on which I could use further clarification:
They also like to know that they are starting with a
full depth
original that can stand up to the pressures of being
converted
ultimately to CMYK for the press.
Is the "full depth original" the raw capture
before setting the contrast range? I have seen digital photographers set
the highlight and shadow points after the capture as they save the image
out in Tiff format. Do digital photographers consider the raw file or the
contrasted version to be the "original" or "master"
image?
Steven Barton
___________________________________________________________________________
Date: Thu, 4 Dec 2003 10:04:02 -0500
From: Ric Cohn
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
I think Martin and Andrew are talking at cross
purposes. Andrew argues that wider gamut spaces are not the problem (no
question). Martin argues that he'd rather not have novices/uneducated users
supplying AdobeRGB because it's too easy for them to hose the
file with a few moves where they rely on the monitor to determine how their
files will look when printed (something I did quite a bit before I learned
how to look at the channels and the numbers). Isn't it more realistic to
have beginners start in a safer space? Those that advance beyond beginner
and care about their color will learn to work in a more challenging
environment.
As I understand it, AdobeRGB came about by accident and
turned out to be a pretty good working space. What about some of the
"designed" spaces. Bruce Lindbloom's BetaRGB (http:
//brucelindbloom.com/), and several others that seem similar. It seems to
me that if we agree that spaces besides ColormatchRGB or SRGB are more
dangerous for beginners we might as well advocate the most efficient spaces
for Color Management Geeks (like myself ;-).
Ric Cohn
http://www.riccohn.com
___________________________________________________________________________
Date: Wed, 3 Dec 2003 19:08:22 -0500
From: Ric Cohn
Subject: CMYK to RGB
I just handled a CMYK to RGB conversion in a (for me)
new way and I thought I'd share it. Anyone else- feel free to tell me if
this is your normal workflow or if you can suggest a better method. I think
it's a good example of combining Dan's methods with color management.
I had an untagged CMYK image which needed to be
repurposed as RGB. My normal workflow has been to look at it in different
preset color spaces, pick what looked best and correct from there. In this
case I was getting ugly results even after spending a good deal of time and
trying several different correction methods. Then, I thought about what I
knew about the original printing of the file: It was prepared to print on
an Iris printer with watercolor paper, and had looked good when originally
printed. I thought of Dan's False Profile method and decided to create a
CMYK profile. I noticed that the file had very high ink limits (over 380)
which I think is why the normal conversions were so ugly.
I went to my Photoshop (CS) color settings> Custom
CMYK and entered numbers that seemed reasonable for this unconventional
file ( I ended up w/ something like: SWOP inks, 390 ink limit, Medium GCR
and 10% Dot Gain). I had to keep closing out the dialog box and
assigning my new profile to the file to see how it looked on screen- going
in this direction I couldn't see any way to use a dialog box with a
preview. Once it looked right I converted to RGB and printed it on an Epson
printer with a custom profile. The file printed better than anything I had
managed with corrections and took much less time.
Ric Cohn
http://www.riccohn.com
___________________________________________________________________________
Date: Wed, 3 Dec 2003 13:22:19 -0000
From: Bob Frost
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers(round 2)
Andrew,
Why do you seem to suggest Colormatch is bigger than
sRGB; they are almost the same size, slightly different shape. Does the
difference in shape make it significantly better that so many people seem
to like Colormatch, but are rude about sRGB, or is it just that sRGB was
created by the dreaded MS (and HP)?
bob Frost.
___________________________________________________________________________
Date: Thu, 04 Dec 2003 10:06:07 +0000
From: Shangara Singh
Subject: RGB Numbers = moral judgment?...
It was 4/12/03 3:37 am, when Ron Kelly wrote:
What's "proper" smacks of a moral judgment;
let's not go there.
Understanding the issues good, pronouncing one option
(yours) "the
correct way" bad.
Ron
How you interpret Andrew Rodney's words rather depends
on the profile and the output device you use to read posts! :-))
If your output device is a church, mandir, synagogue,
gurudrawra, etc, then "proper" can, in some circumstances, imply
moral judgement.
If your output device is a group devoted to discussing
color theory, then in that context it does not "smack of moral
judgement." Furthermore, since the post is referring to "some
users," and not any particular user, I fail to see how anyone using a,
um, proper profile can interpret the words as a moral judgement. Even if
you use an incorrect profile, it has to be seriously corrupted for it to
translate "proper" into "moral judgement," given the
context and the audience.
When I read newsgroups, I use the English profile
Smethwick Hall Boys School (1967) and it translated "proper" to
mean "correct." Of course, I always make sure the "Religious
Upbringing" option is NOT selected; especially when reading
newsgroups. I also select "Don't take anything you read
seriously," because it helps to produce natural looking skintones and
avoids the overly red skintones you can get when you use, erm, a false
profile! :-))
Oxford English Dictionary:
Proper - 1. Belonging to Psalms, lessons. 2. Accurate,
Correct.
[f.L, proprius One's own, special]
--/ Shangara Singh.
___________________________________________________________________________
Date: Thu, 04 Dec 2003 12:34:24 -0700
From: Andrew Rodney
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers(round 2)
on 12/3/03 6:22 AM, Bob Frost wrote:
Andrew,
Why do you seem to suggest Colormatch is bigger than
sRGB; they are almost
the same size, slightly different shape. Does the
difference in shape make
it significantly better that so many people seem to
like Colormatch, but are
rude about sRGB, or is it just that sRGB was created by
the dreaded MS (and
HP)?
It1s a tad bigger. Nothing to really write home about.
Because I used PressViews (later Barco and now Sony Artisan displays),
ColorMatch RGB is a slightly better fit but there are some advantages to a
2.2 gamma editing space (it1s more even). So for users who are not using
color management or viewing on a Mac outside of an ICC savvy application,
ColorMatch will preview pretty well.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Thu, 04 Dec 2003 14:30:39 -0800
From: "Jeff Smith"
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
Steven Barton wrote:
Is the "full depth original" the raw capture
before setting the contrast
range? I have seen digital photographers set the
highlight and shadow points
after the capture as they save the image out in Tiff
format. Do digital
photographers consider the raw file or the contrasted
version to be the
"original" or "master" image?
The answer is yes<g>
Shooting primarily in the studio using an eyelike back
and proprietary software, the on-screen preview reflects the curve
adjustments and highlight/shadow points we set prior to capture. These
curves can be changed while previewing the capture, if needed. The software
actually stores the raw data without adjustment and applies the curve
during processing. we always archive the original galley data (raw data on
all captures from a session) as well as the final processed image files.
The gallery files are the 'master files that are saved. Equivalent to a
digital negative.
We also archive the final processed images for
reference.
Since the gallery is stored intact, we can always
reopen a capture file after the fact, make whatever curve adjustments we
need and reprocess for output to another device. The client rarely sees a
truly linear image preview, if ever. Additional curve adjustment sets can
be saved, named for the output device intended, and recalled for use at any
time
in the future.
Does that help?
Jeff Smith
Smith/Walker Design and Photography
P. O. Box 58630
Seattle, WA 98138
ph: 206-575-3233
___________________________________________________________________________
Date: Thu, 4 Dec 2003 19:39:55 -0000
From: Bob Frost
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
From: "Ric Cohn"
Isn't it more realistic to have
beginners start in a safer space? Those that advance
beyond beginner
and care about their color will learn to work in a more
challenging
environment.
Ric,
Of course it is; that is one of the reasons why MS and
HP invented sRGB as the standard color space that all scanners, monitors
and printers (inanimate variety) could cope with. But I don't think Martin
is talking about beginners; quite the opposite. He seems to be talking
about the generation (?) gap between professionals who can and those who
can't (to pinch Canon's line).
Even amateurs like me can progress to, and understand,
and use color management correctly; it's not 'rocket science'.
Bob Frost.
___________________________________________________________________________
Date: Thu, 04 Dec 2003 12:23:21 -0700
From: Andrew Rodney
Subject: Re: Re: Photoshop CS defaults, was: RGB
Numbers (round 2)
on 12/4/03 10:54 AM, Scott Larsen wrote:
I'm not against knowing what to do in all cases, but
the fact is that
more than 99% of the images I work with will be CMYK.
Should I
expend significant time and energy and storage space on
wide-gamut versions of my scans "just in
case" something changes
in a decade? No.
I have no problem with that. You have made the decision
not to worry about 1% of future output. That1s not the case with a lot of
users (especially photographers).
Keep in mind that the wider gamut file doesn1t tax your
system any more than the smaller gamut file. That you have made the
decision not to worry about 1% is still totally viable.
My company does have a website, and does
occasionally produce inkjet prints, so I do need to
know how to
handle these, but my bread and butter is CMYK and if a
particular
scenario is promoted as best for CMYK at the expense of
other
output possibilities, I'll still opt for it.
My argument is that sRGB simply is NOT best for CMYK
and I1d like to see anyone prove otherwise by CORRECTLY taking files in
both colorspaces (sRGB and Adobe RGB) with a good representation of color
images (from neutrals to pastel to very saturated) prove that sRGB will be
better. In fact even of both are the same when ink hits paper, what1s the
harm of a larger gamut file that will very likely be more useful for other
output devices? What about when someone wants to reprint the job but use
Hexachrome? That process certainly hasn1t been all the popular (it1s darn
expensive) but who knows what kinds of printing process we1ll have in the
next 5 or 10 years?
Bottom line here (and then I think I1m finished),
there1s no reason why sRGB is any better (and might be worse if nailing
Cyan1s and greens are important) than Adobe RGB! IF you feel more
comfortable using sRGB I have no problem with that but thousands, perhaps
hundreds of thousands of images have been reproduced ink on paper from
Adobe RGB since Photoshop 5 shipped and until recently, I haven1t heard
people saying there was some inherent danger (other than improper file
handling and good CMS practices) with this colorspace. It1s simply too easy
to blame the space when the fault is from the user. Instead of spending all
this time blaming the space and advising people to use a space that does
have more limitations for future output, why not simply teach the correct
way to use ANY RGB Working Space and educate people when they are best
used. As I1ve said, there are NO perfect Working Spaces.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Thu, 4 Dec 2003 21:02:21 -0700
From: Chris Murphy
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
On Dec 3, 2003, at 7:47 AM, Dan Margulis wrote:
Five years ago, a number of "experts" thought
that even Adobe RGB wasn't
wide-gamut enough and that something even more colorful
was necessary. While that
view isn't dead, many fewer people hold it now, so I
think it's fair to call
it an idea whose time has come and gone.
I don't entirely agree. For traditional print gamuts,
perhaps. But I think there is value in high-bit wide gamut RGB spaces. The
problem isn't really with the size of the gamut but that today's color
management is ill equipped for dealing with the substantial amount of gamut
compression needed to do a decent job when converting the image to a
destination with a much smaller gamut.
But even in a practical context, though comparatively
rare, there are companies that print with fluorescent inks and get enormous
improvements in the gamut. That there are other problems pertaining to
measurement and the computation of gamut mapping when using such ink sets
is a little too academic for this discussion, but these workflows do exist.
To fully take advantage of them necessitates using wider gamut RGB spaces.
Otherwise, yes it's easy to suggest most people steer
clear of wide gamut RGB spaces if you don't understand their pitfalls, and
that of ensuing conversions.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Fri, 5 Dec 2003 08:59:36 -0800 (PST)
From: pictureelements
Subject: Re: RGB CMYK conversion
Hi Dan Margulis
Thanks for the info. Is there by chance any additional
information, such as books or urls to get specific math for building the
luts and conversion?
Steven Scott ASA
___________________________________________________________________________
Date: Fri, 5 Dec 2003 15:49:19 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Bob Frost writes,
I fully understand that I won’t be able to see
all those colors on my
current monitors, or print them on my current printer,
and that I will need
to use softproofing with good custom profiles to
finalise my images, but
that is no reason for throwing away those colors that
are in the real world
and on film and in camera output.
This is an excellent restatement of Terry Wyse’s
points as to the advantages of wider-gamut RGBs. As for the disadvantages,
Terry’s post lists them as well, and they are also succinctly
summarized by Steven Barton.
You seem to be concerned with what may happen 15 years
from now. That’s also the case with many of the photographers I
teach. The class I am teaching today, by contrast, consists of seven people
who have a) with a single exception, zero concern with any output other
than conventional print; b) without exception, zero interest in what
happens more than a year from now to the images they work on today.
A wider-gamut RGB may be right for you. It may or may
not be right for other photographers. It would certainly be wrong for this
group. Different users need different settings.
Just because some people do not understand color
management, or are just
averse to change and do not want to understand color
management, does not
mean that it is nonsense and that people who do use it
should be ridiculed
so often as you seem to do.
This of course has nothing to do with the thread.
Someone with sRGB as their working space uses neither less nor more
“color management” than someone using Adobe RGB.
For the record, however, I would agree that many of the
people who have been promoting “color management” over the
years have demonstrated that they really don’t understand the
concept. Otherwise, they would not have been proven wrong as often as they
have been, and would not find themselves in the embarrassing position that
they do today, where they have to reverse course and embrace positions that
they’ve been ridiculing me for years for holding.
I would agree also that “averse to change”
has been a good general description of color management zealots over the
years, with certain happy exceptions such as Chris, Terry, and Jim. In our
field, capabilities, techniques, and client objectives are changing
rapidly. Some service providers and photographers have shown that they are
capable of adapting to the new realities. The most prominent color
management advocates, by contrast, have consistently been mired in the
past, resistant to any sort of evolution in their philosophy and especially
to any admission that any part of it has become obsolete. As a result, they
are often late to see new opportunities, and years behind the times in
their recommendations.
How come it took the zealots so many years to see that
photographers needed to take control of the print process by learning both
CMYK and RGB? Why were they so slow to embrace contract proofing on the
desktop, and the power of digital cameras? Why did it take so many years
for them to appreciate that color management in the absence of process
control is pointless? How come the suggestions for innovative use of the
technology that get widely adopted, such as assigning a profile based on
the image and not on the image’s source, come from me and not from
them? Why did it take so many years for them to appreciate what a
catastrophe Photoshop 5 was for color management, and that the debacle was
in no way the fault of the lazy users or the conspiracy among printers that
they first imagined?
On this list itself, just two years ago Andrew Rodney
was berating me for not believing in camera profiling, something he now
concedes on the ColorSync list doesn’t work. Just one year ago, as I
mentioned earlier, he was denouncing me for suggesting that color
management supporters were moving toward the positions of Chris and Terry.
And of course, he’s spent years pursuing the fantasy that embedded
profiles will become a reliable way for strangers to interchange documents,
which idea Adobe has just buried with Photoshop CS.
Just remember what happened to the dinosaurs; the world
changed, and they
wouldn’t or couldn’t.
I hope this will not happen to Andrew. Although so many
of his pet theories have become extinct that they could make a Jurassic
Park of color, one shouldn’t give up hope. Meanwhile, he and some of
his extremist friends serve as a valuable lesson to the rest of us. They
have been so frequently wrong, and so frequently out of date, over so long
a period of time that it must both reassure anyone who’s having
self-doubt about their own color knowledge, and serve as a caution to
anybody else who starts preaching to the world about technologies that they
have neither the experience nor the background to fully grasp.
Dan Margulis
___________________________________________________________________________
Date: Fri, 05 Dec 2003 16:33:11 -0800
From: John Denniston
Subject: RGB Numbers
The concerns everyone is having about archiving
pictures with a profile that will be compatible for future use seems to be
jumping over an obvious solution.
If understand the problem correctly, assigning a
limited gamut profile today will lead to image degradation or
misinterpretation in the future if wide gamut printers and displays become
available and a conversion has to be made.
Wouldn’t it be prudent then to archive the
original without any profile at all (PS4) but with a reference colour
corrected thumbnail attached to it which has a known colour space, say
sRGB. When the archived file is opened in the future to a wide gamut
working space it can be colour corrected to match the reference thumbnail
and assigned a profile appropriate for the period of time.
True there would some unknown colours but there are
unknown colours now in wide gamut spaces because we have no way of
displaying them properly but at least with this system we would have the
chance to make intelligent choices with reference to how the picture is to
be printed.
John Denniston
www.dirtbikephoto.com
www.dennistonphoto.com
___________________________________________________________________________
Date: Fri, 5 Dec 2003 16:01:57 EST
From: Dan Margulis
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Chris Murphy writes,
For traditional print gamuts, perhaps. But I
think there is value in high-bit wide gamut RGB spaces.
The problem
isn’t really with the size of the gamut but that
today’s color
management is ill equipped for dealing with the
substantial amount of
gamut compression needed to do a decent job when
converting the image
to a destination with a much smaller gamut.
There’s value in the wide-gamut spaces (not,
AFAIK, in the extra bits), especially in dealing with situations like the
ones you mention with fluorescent inks etc. The point about gamut
compression is well taken but the real drawback to my mind is that
they’re difficult to work with, since any small move makes a much
greater change than it would in sRGB or the like. This is the same problem
with correcting in LAB, but LAB is so dissimilar to sRGB that it offers a
lot of new opportunities. An ultra-wide-gamut RGB has the same strengths
and weaknesses as sRGB, it just is harder to control. But I agree that
people should know how to use them.
But even in a practical context, though comparatively
rare, there are
companies that print with fluorescent inks and get
enormous
improvements in the gamut. That there are other
problems pertaining to
measurement and the computation of gamut mapping when
using such ink
sets is a little too academic for this discussion, but
these workflows
do exist. To fully take advantage of them necessitates
using wider
gamut RGB spaces.
Fair enough. But the point of what I was saying was,
five years ago there was a substantial view among your color-management
devotee friends that people should be using this kind of ultra-wide RGB as
a workspace for more standard destinations. There are still a few people
who think that but it’s now definitely a small minority.
Dan Margulis
___________________________________________________________________________
Date: Sat, 06 Dec 2003 06:14:45 -0700
From: Andrew Rodney
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
on 12/5/03 1:49 PM, Dan Margulis wrote:
On this list itself, just two years ago Andrew Rodney
was berating me for not
believing in camera profiling, something he now
concedes on the ColorSync
list doesn’t work.
You are NOT reading the CS list correctly again Dan
because I1ve said nothing of the kind!
I1d be happy to correct and clarify the statement but
it1s OT to some degree but once again, as you1ve done in the past, you1ve
misread or misunderstood everything I1ve said on this subject (Camera
Profiling) if you1re going to say I said this. You MUST profile a file
otherwise the numbers have no meaning and the process I1ve recommended to
many DSLR users who shoot RAW files is to use a product that DOES use
profiles (two in fact) and does color manage the files. PLEASE get your
facts straight if you1re going to mention MY name with a comment.
Just one year ago, as I mentioned earlier, he was
denouncing
me for suggesting that color management supporters were
moving toward the
positions of Chris and Terry. And of course, he’s
spent years pursuing the
fantasy that embedded profiles will become a reliable
way for strangers to interchange
documents, which idea Adobe has just buried with
Photoshop CS.
I still stand by that since all untagged files are
simply numbers with no meaning. I can1t understand how you can take any
untagged file I give you and figure out what I provided. But we1ve been
down this path before and no matter how often I suggest that providing info
about a file is always better than not, you hum loudly, trying to drum out
the sound of my logic.
Just remember what happened to the dinosaurs; the world
changed, and they
wouldn’t or couldn’t.
I hope this will not happen to Andrew. Although so many
of his pet theories
have become extinct that they could make a Jurassic
Park of color, one
shouldn’t give up hope.
Dan, time will tell who I suggest you might want to
look at the history of color and color management and look at your own
track record.
Meanwhile, he and some of his extremist friends serve
as a
valuable lesson to the rest of us. They have been so
frequently wrong, and so
frequently out of date, over so long a period of time
that it must both
reassure anyone who’s having self-doubt about
their own color knowledge, and serve as a caution to anybody else who
starts preaching to the world about technologies
that they have neither the experience nor the
background to fully grasp.
I1d ask you to provide some specifics but you1ve so far
misquoted me on so many occasions that I have to simply believe you are not
at all interested in understanding the other guy1s point, have to 3be
right2 and have a tendency to ignore a good deal of the English presented
before you (at least in eamil form). If you want to call people extremists,
by all means. If you would however be more careful about being accurate,
many would be appreciative.
Fair enough. But the point of what I was saying was,
five years ago there was
a substantial view among your color-management devotee
friends that people
should be using this kind of ultra-wide RGB as a
workspace for more standard
destinations. There are still a few people who think
that but it’s now definitely
a small minority.
Fair enough IF what you say is true (and I don1t think
it is and I1d like to see you post anything from these extremist
calibrationist that recommended ulta-wide gamut spaces WITHOUT warning1s to
the downside). Come on Dan, put up. Where in print (ink on paper or Web)
can we find this shocking advise?
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Sat, 06 Dec 2003 06:14:56 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/5/03 5:33 PM, John Denniston wrote:
If understand the problem correctly, assigning a
limited gamut profile
today will lead to image degradation or
misinterpretation in the future if
wide gamut printers and displays become available and a
conversion has to
be made.
No, it will not lead to image degradation. It will
limit the colors you can reproduce in the future. But the image tomorrow
will reproduce as it did today within that limitation.
Wouldn’t it be prudent then to archive the
original without any profile at
all (PS4) but with a reference colour corrected
thumbnail attached to it
which has a known colour space, say sRGB.
A profile IS a reference. It simply tells us what the
numbers in our file should appear as on screen or on output (with yet
another profile to get the output numbers).
Photoshop 4 thought your RGB files where in some
unknown colorspace that was your unique monitor (in whatever condition it
happened to be in) and everyone1s monitor is totally different. Not only is
the meaning of the numbers incorrect but the same set of numbers will
appear differently on each monitor and each conversion will be different IF
you use the old PS4 logic of doing an RGB to CMYK conversion (which says,
the source is 3My Monitor2 and everyone1s monitor is different). Would you
really like to see two completely different users take the identical
numbers and use the identical conversion method only to find they get two
different sets of CMYK values? That1s exactly what Photoshop used to do.
When the archived file is opened
in the future to a wide gamut working space it can be
colour corrected to
match the reference thumbnail and assigned a profile
appropriate for the
period of time.
Thumbnail based on what? It too is just a bunch of
numbers.
True there would some unknown colours but there are
unknown colours now in
wide gamut spaces because we have no way of displaying
them properly but at
least with this system we would have the chance to make
intelligent choices
with reference to how the picture is to be printed.
The reference is the profile which does NOTHING more
than tell us the colors those numbers represent.
Numbers don1t tell us what colors look like. That1s the
part of color theory (computer color theory) some here don1t want to
discuss and educate. 233/67/98 doesn1t tell us anything about color
appearance, only what ingredient a pixel is. You can have that set of
number produce quite different color appearance. Take an RGB or CMYK file
(it1s just numbers right) and assign different profiles. Watch the colors
change before your eyes. The numbers haven1t changed one lick. The color
appearance (and what you1ll get) can change radically. This clearly
illustrates why we need profiles for a value system (numbers) that don1t
tell us what colors look like without the translator (the profile).
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Sat, 6 Dec 2003 10:29:02 EST
From: Paul Harding
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round 2)
Come on fellas!!! Can’t we all be friends?
Paul Harding
Jit Graphics
___________________________________________________________________________
Date: Sat, 06 Dec 2003 16:35:03 +0000
From: “Aaron Hill”
Subject: Debate
It is amazing to read so much passion and intensity
about color. This is both good and bad. I think we should all remember
that, although knowledge and understanding are important, it is relatively
unimportant in the scheme of things. Obviously some of these arguments have
become personal. Please just report the facts, and then the reader can make
a judgment for himself.
Thanks.
Aaron Hill
___________________________________________________________________________
Date: Sat, 06 Dec 2003 13:59:29 -0800
From: John Denniston
Subject: Re: RGB Numbers
I’m not advocating ignoring profiles but the use
of a common, sRGB, profile in a “colour corrected preview
thumbnail” so that raw files (nef’s or whatever) could be
opened at some future date into what ever working spaces are appropriate
and colour corrected to match a known standard. I think this would be
easier to implement than getting the entire world to agree on archiving
tiff’s to an exotic wide gamut colour space.
John Denniston
www.dirtbikephoto.com
www.dennistonphoto.com
___________________________________________________________________________
Date: Sat, 6 Dec 2003 14:34:02 -0800
From: “Mike Russell”
Subject: Re: Debate
Aaron Hill wrote:
It is amazing to read so much passion and intensity
about color. This
is both good and bad. I think we should all remember
that, although
knowledge and understanding are important, it is
relatively
unimportant in the scheme of things. Obviously some of
these
arguments have become personal. Please just report the
facts, and
then the reader can make a judgment for himself.
Nice thought, but...
Yours is the eternal cry in the Internet wilderness.
This is because you are asking for something that would destroy the
fun part for some of us.
Ever read about what Van Gogh had to say about his
purples and yellows? The term “Impressionist” itself came
from a particularly scathing review of the first showing of this new
style of painting. Picasso’s first works, shown by Stieglitz in
NYC, went back to Paris mostly unsold, and with very scathing, personal
reviews.
Humanity’s accomplishments, even minor ones like
the handling of color in our photographs, are fueled by passion. If you
deprive usof it, we’d find something else to devote our *selves* to.
Mike Russell
www.curvemeister.com
www.geigy.2y.net
___________________________________________________________________________
Date: Sat, 06 Dec 2003 15:07:23 -0800
From: Steven Barton
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
Jeff Smith wrote:
The software
actually stores the raw data without adjustment and
applies the curve during
processing. we always archive the original galley data
(raw data on all
captures from a session) as well as the final processed
image files. The
gallery files are the ‘master files that are
saved. Equivalent to a
digital negative.
Jeff, I appreciate this information. Can you clear up
one other matter for me? I assume that each capture device has its own
color space. Is the ‘raw’ image then taken from its own camera
space into a “known” color space, such as Adobe RGB or Apple
RGB, to have the desired curve adjustments applied and tagged with that
profile to identify the working color space used?
I would further assume that the color values from the
camera “space” would be “converted” to those of the
known color space rather than simply allowing the Adobe or Apple RGB space
apply its own characteristics to the image.
Is that how digital photography is typically handled?
Thanks,
Steven Barton
___________________________________________________________________________
Date: Sat, 6 Dec 2003 15:45:52 -0800
From: David Cardinal
Subject: RE: Photoshop CS defaults, was: RGB Numbers
(round2)
Jeff, I appreciate this information. Can you clear up
one
other matter for me? I assume that each capture device
has
its own color space. Is the ‘raw’
image then taken from its own camera space into a
“known”
color space, such as Adobe RGB or Apple RGB, to have
the
desired curve adjustments applied and tagged with that
profile to identify the working color space used?
To jump in here, the raw data is not even in RGB (at
least in cameras which provide true raw files). It is the individual sensor
readings for each sensor element. The raw data has to be de-mosaiced at a
minimum before you even wind up with RGB values at each pixel.
The Raw data is also almost always linear and has to be
gamma corrected. Colors can be way out of whack as well depending on the
filters. These two adjustments can be made in the way you
described—as an input space using a profile to convert to a known
space—but often they are done with specific algorithms (in the camera
in particular they are performed by code in the
firmware).
I would further assume that the color values from the
camera
“space” would be “converted” to
those of the known color
space rather than simply allowing the Adobe or Apple
RGB
space apply its own characteristics to the image.
Assuming you have a known camera space. The tricky part
is figuring out what to profile. I profile my cameras in JPEG mode (using
ColorEyes) and then convert to Adobe RGB during the workflow. If you want
to skip the custom profiling step many high-end cameras will also shoot
“natively” to what they call Adobe RGB (although of course they
are not exact) and consumer versions aim to produce sRGB. Starting with Raw
files gives you more flexibility, but profiling a cameras raw output is
much trickier. Most of the packages I’ve tried (ProfileMaker, for
example) didn’t seem able to create a usable profile for the Raw
linear sensor data, even after it was interpolated.
Hope that helps a little!—David
___________________________________________________________________________
Date: Sat, 6 Dec 2003 21:18:50 -0700
(GMT-07:00)
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/6/03 2:59 PM, John Denniston wrote:
I’m not advocating ignoring profiles but the use
of a common, sRGB, profile in a “colour corrected preview
thumbnail” so that raw files (nef’s or whatever) could be
opened at some future date into what ever working spaces are appropriate
and colour corrected to match a known standard. I think this would be
easier to implement than getting the entire world to agree on archiving
tiff’s to an exotic wide gamut colour space.
Thatas in place today when (on some cameras) you shoot
RAW+JPEG. The matrix setting you pick on say a Canon 1Ds controls the JPEG
(so you would get RAW plus a JPEG file in either sRGB or Adobe RGB). But
the RAW file is RAW and has to at some point be converted into a real color
file with some tag. Despite Danas complete misunderstanding of what I wrote
on the ColorSync list, thatas exactly what Adobe Camera RAW would and could
do using itas internal profiles. Youad be able to end up in one of four RGB
Working Spaces.
Problem! The RAW conversion and the JPEG (even if both
told to go into the same colorspace (letas say sRGB) would NOT match either
visually or numerically. So that JPEG is only useful for printing out small
proofs or better for quick viewing for file editing.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
___________________________________________________________________________
Date: Sat, 6 Dec 2003 16:07:50 -0800
From: Paul D. DeRocco
Subject: RE: RGB Numbers
From: John Denniston
I’m not advocating ignoring profiles but the use
of a common, sRGB, profile
in a “colour corrected preview thumbnail”
so that raw files (nef’s or
whatever) could be opened at some future date into what
ever working spaces
are appropriate and colour corrected to match a known
standard. I think
this would be easier to implement than getting the
entire world to agree on
archiving tiff’s to an exotic wide gamut colour
space.
This makes no sense to me. Being able to open an image
and have the colors come out right is exactly what embedded ICC profiles
are for. I don’t know what kind of “short cut” or
alternative you’re trying to come up with, but embedding a profile is
about as simple as you can get.
Ciao,
Paul D. DeRocco
___________________________________________________________________________
Date: Sat, 6 Dec 2003 17:39:23 -0600
From: Mike DeSantis
Subject: Re: Debate
Good Evening,
I have to agree with Aaron.
For crying out loud, passion is a great thing to have in life, but there
are many more important things in life. Be passionate about color, but keep
your integrity and character intact. Not to pick on Picasso, as much as I
enjoy his art, but in a few hundred mores years, the critics may be against
him again. If we keep this forum to discussion about color, we’ll all
benefit, both the teachers and the students. Name-calling just divides our
group. Knock it off or there may be coal coming your way. And no, I
don’t want to discuss what profiles Mr. Kringle uses up there in the
Northern Lights
Mike DeSantis
DeSantis Photography
www.desantisphotography.com
___________________________________________________________________________
Date: Sat, 06 Dec 2003 22:55:03 -0800
From: John Denniston
Subject: RE: RGB Numbers
At 04:07 PM 06/12/2003 , Paul wrote:
I don’t know
what kind of “short cut” or alternative
you’re trying to come up with, but
embedding a profile is about as simple as you can get.
It’s not a shortcut. There seemed to some concern
about archiving files in the largest gamut possible so future methods of
printing or colour correction can be taken advantage of. RAW (of NEF) has
the largest gamut but one is never sure how the image is to be acquired and
there are also problems, at least with the files I deal with, of colour
shifts in the shadows plus the dreaded magenta cast in skin tones. I
suggest saving a colour corrected sRGB preview with the RAW file so that 30
years from now the RAW file could be opened and colour corrected using the
preview as a reference. For day to day production it doesn’t have
much use but for museums, archivists or art galleries who are more
concerned with the next generation than this one it might be a more
reliable system than archiving colour corrected pictures as a wide gamut
tiff.
Regards, John
John Denniston
www.dirtbikephoto.com
www.dennistonphoto.com
___________________________________________________________________________
Date: Sat, 06 Dec 2003 10:29:45 -0800
From: John Denniston
Subject: Re: RGB Numbers
At 05:14 AM 06/12/2003 , Andrew wrote:
This clearly illustrates why we need
profiles for a value system (numbers) that don1t tell
us what colors look
like without the translator (the profile).
I’m not advocating ignoring profiles but the use
of a common, sRGB, profile in a “colour corrected preview
thumbnail” so that raw files (nef’s or whatever) could be
opened at some future date into what ever working spaces are appropriate
and colour corrected to match a known standard. I think this would be
easier to implement than getting the entire world to agree on archiving
tiff’s to an exotic wide gamut colour space.
Regards, John
John Denniston
___________________________________________________________________________
Date: Sun, 7 Dec 2003 05:58:19 -0700
(GMT-07:00)
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/6/03 11:55 PM, John Denniston wrote:
RAW (of NEF) has the largest gamut
but one is never sure how the image is to be acquired
and there are also
problems, at least with the files I deal with, of
colour shifts in the
shadows plus the dreaded magenta cast in skin tones.
The “dreaded” magenta skin is completely
due to the wrong description of the numbers and is fixed with correct
profiles!
An example can be seen here:
http:
//digitaldog.imagingrevue.com/files/SkintoneRawvsprofile.jpg
The two images have IDENTICAL numbers! The only
difference is the image on the right received a tag from a custom profile
while the one on the left is assigned the profile the camera tells us it
really got shot under (which is just not accurate). This is from a D1.
The web is not color managed but you will get the idea.
Note that the image on the left appears to have blown out highlights. This
is simply the incorrect meaning of the numbers (profile) playing a cruel
trick on Photoshop. Again, the data is just fine, there’s no need to
play color theory correction tricks. A simply assignment of the correct
profile “fixes” the issues in a split second with no change in
numeric values or degradation of the image.
This is why I find it SO amusing that some are so
hostile to the idea of profiles and would rather write and lecture about
how to edit values which are simply being shown wacked out. Image editing
is certainly necessary. But smart Photoshop users first determine if the
problem can be solved with proper color management since what we see and
what were are told by Photoshop can be way off IF the profile assignment is
either faultily or missing.
I suggest saving a
colour corrected sRGB preview with the RAW file so that
30 years from now
the RAW file could be opened and colour corrected using
the preview as a
reference.
Not possible. The RAW file is a Grayscale file. There
is NO color to match until its processed and how it’s processed will
play a huge role. Think of this like digital clay. It’s quite similar
to the PhotoCD YCC image pack we had years ago which was totally dependant
on how the image was acquired and converted from YCC to some RGB
Colorspace.
Andrew Rodney
http://www.imagingrevue.com/
The Digital Dog
30 Gavilan Road
Santa Fe, NM 87508
505-577-0116
___________________________________________________________________________
Date: Sun, 07 Dec 2003 12:10:59 -0500
From: David Chusid
Subject: Re: Photoshop CS defaults, was: RGB Numbers
(round2)
I’d like to know more about the
“downside” of using a wider-gamut RGB space such as Adobe RGB.
I’m currently using sRGB as a working space. My
primary output device is an 8-color ink jet, a Colorspan DisplayMaker XII
with Endurachrome (dye) inks. Secondarily, I occasionally prepare
jobs for conventional 4/c offset printing. I think it’s possible that
the Colorspan may have a somewhat wider gamut than offset printing, because
I think the inks may be better than their offset equivalents. In any
case, I certainly don’t want to sacrifice any part of the CMYK gamut,
and this thread has suggested that I may be doing that by working in sRGB.
I use the GM Eye-One system to create profiles (the
Colorspan RIP is an RGB device). I’m happy with the consistency of
color between the monitors and the printer. What do I have to watch out for
if I switch my working space to Adobe RGB?
Thanks,
David Chusid
___________________________________________________________________________
Date: Sun, 7 Dec 2003 10:25:41 -0800
From: Paul D. DeRocco
Subject: RE: RGB Numbers
From: John Denniston
It’s not a shortcut. There seemed to some concern
about archiving files in
the largest gamut possible so future methods of
printing or colour
correction can be taken advantage of. RAW (of NEF) has
the largest gamut
but one is never sure how the image is to be acquired
and there are also
problems, at least with the files I deal with, of
colour shifts in the
shadows plus the dreaded magenta cast in skin tones. I
suggest saving a
colour corrected sRGB preview with the RAW file so that
30 years from now
the RAW file could be opened and colour corrected using
the preview as a
reference. For day to day production it doesn’t
have much use but for
museums, archivists or art galleries who are more
concerned with the next
generation than this one it might be a more reliable
system than archiving
colour corrected pictures as a wide gamut tiff.
Maybe I’m beating a dead horse, but I still
don’t get it. If you have an image in digital form, it already has a
particular color space. It is what it is. There is no benefit to converting
it to some larger color space in anticipation of something in the future,
because it will still contain the same colors—it will just use
different numbers, with less distance between them, to represent those
colors. So as long as you provide a profile that describes that color
space, you’ve preserved all the information that there is to
preserve.
If you’re opening a raw file, and seeing colors
you don’t like, then whatever you’re using to convert the file
has an inaccurate profile for the camera. The solution to that it is to get
a better profile. For instance, CaptureOne allows you to specify a camera
profile, and it comes with built-in profiles for various cameras. If you
convert a Nikon raw file, and get magenta skin tones, then the solution
would be to use software that allows an explicit profile to be selected,
and use profiling software to build a better profile for the Nikon camera
(or obtain one from someone else who’s already done it). Then,
you’ll have a raw file plus an accurate ICC profile that describes
its color space, which will be as valid thirty years from now as it is
today.
Ciao,
Paul D. DeRocco
___________________________________________________________________________
Date: Sun, 07 Dec 2003 12:10:31 -0800
From: John Denniston
Subject: Re: RGB Numbers
At 04:58 AM 07/12/2003 , Andrew wrote:
Not possible. The RAW file is a Grayscale file. There
is NO color to match
until its processed and how it’s processed will
play a huge role.
If it’s possible to acquire and colour correct a
RAW file today why would it be impossible to do the same 30 years from now.
John Denniston
www.dirtbikephoto.com
www.dennistonphoto.com
___________________________________________________________________________
Date: Sun, 7 Dec 2003 16:17:45 -0500
From: “Michael Demyan”
Subject: RE: RGB Numbers
You will also have to remember to save the RAW
converter with these files in the same subdirectory. 30 years from now that
converter may not be in existence. Hopefully - Hopefully the systems 30
years from now will be able to read the file formats that we are using
today.
This requires a concerted effort of updating files
every 3 to 5 years so the current systems will be able to read the files.
Michael C. Demyan
Fine Photography & Digital Graphic Design
www.mikedemyan.com
www.pbase.com/mdemyan
___________________________________________________________________________
Date: Sun, 7 Dec 2003 16:59:37 -0800
From: Paul D. DeRocco
Subject: RE: Photoshop CS defaults, was: RGB Numbers
(round2)
From: David Chusid
I’d like to know more about the
“downside” of using a wider-gamut
RGB space such as Adobe RGB.
I use the GM Eye-One system to create profiles (the
Colorspan RIP
is an RGB device). I’m happy with the consistency
of color
between the monitors and the printer. What do I have to
watch out
for if I switch my working space to Adobe RGB?
The only problem I can think of is that when you
ultimately convert back to a narrower gamut for display or printing, the
conversion will desaturate your colors a little to “make room”
for all those even more saturated colors that are theoretically possible,
even though the image doesn’t really contain them. I’ve run
some tests in PS, and found that this happens in all four rendering
intents, both in ACE and ICM. (Don’t have a Mac, so I can’t try
ColorSync.)
You can see this for yourself if you create an image in
PS filled with pure green (0,255,0) and assign your monitor profile to it,
so that no translation is performed on the way to the display. If you then
convert to Adobe RGB, which has a wider gamut than any typical monitor in
the green direction, you might expect no change—after all, Adobe RGB
can indeed represent the color in question with no loss—but instead,
you immediately see the green get duller, for the reason mentioned above.
Ciao,
Paul D. DeRocco
___________________________________________________________________________
Date: Sun, 7 Dec 2003 18:07:10 -0800
From: David Cardinal
Subject: RE: RGB Numbers
Not possible. The RAW file is a Grayscale file. There
is NO
color to match until its processed and how it’s
processed
will play a huge role. Think of this like digital clay.
It’s
quite similar to the PhotoCD YCC image pack we had
years ago
which was totally dependant on how the image was
acquired and
converted from YCC to some RGB Colorspace.
If someone wanted to save a “key” with the
Raw data, I’d personally save the spectral response data (e.g.
response to light of each frequency) for the camera sensor/filter. With
that key plus the sensor data it is possible to reconstruct the image. Of
course, I don’t know of any camera company that publishes that data.
I’ve measured it for the D1X, but it takes a bunch of equipment &
time. It’d be nice if it was published the same way Kodak, Agfa and
Fuji publish their film response curves!
—David Cardinal
Pro Shooters LLC
http://www.proshooters.com
http://www.nikondigital.org
___________________________________________________________________________
Date: Sun, 07 Dec 2003 17:53:52 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/7/03 1:10 PM, John Denniston wrote:
If it’s possible to acquire and colour correct a
RAW file today why would
it be impossible to do the same 30 years from now.
It1s not possible to have the in camera on the fly
conversion to 3sRGB2 (or 3Adobe RGB 19982) and the same conversion using a
converter match each other (certainly today). It1s hard enough to figure
out how the cameras do their proprietary conversions from their raw format
(something Knoll had to figure out on his own to do Camera RAW). These guys
are not likely to supply how they do the conversions IN CAMERA which is
firmware!
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Sun, 07 Dec 2003 17:26:59 -0800
From: John Denniston
Subject: RE: RGB Numbers
At 10:25 AM 07/12/2003 , Paul wrote:
If you’re opening a raw file, and seeing colors
you don’t like, then
whatever you’re using to convert the file has an
inaccurate profile for the
camera. The solution to that it is to get a better
profile.
Which is very easy to do today because we can look at
the object we just photographed and see if the colours we acquired from the
RAW file are correct. Thirty years from now the object photographed might
not exist and if it’s art work the colours might not be obvious so a
decision about which profile to use becomes a problem. Hence the idea of
having an sRGB colour corrected preview filed with it.
The clitch is, as Michael points out, will ANY of these
spaces, formats or Photoshop exist in 30 years.
Regards, John
John Denniston
www.dirtbikephoto.com
www.dennistonphoto.com
___________________________________________________________________________
Date: Sun, 7 Dec 2003 20:19:16 -0600
From: N9VJG
Subject: Re: RGB Numbers
Greetings Andrew and the group:
I find your solution compelling. However, I’m
confused. I downloaded the file and found an embedded ColormatchRGB
profile—not the custom D1 input profile. Then I checked both images
with the densitometer tool and the numbers were quite different. Obviously,
the images look different. What am I missing?
Regardless, I spent about 15 minutes trying to match
and improve upon the results shown in the D1 custom input profile. I was
using curves, selective color and a funky layer blend. I did a tiny
selection with her cheeks and history brush with the hair. Didn’t get
it exact. It needs more work. Although the custom profile fix was
exceptional, it seemed a bit too dense.
http://www.abetterreality.net/EricsHumbleAttempt.JPG
—
Eric Curtis M. Basir (Bond)
Photo Grafix
http://www.abetterreality.net
(847) 673-7043
___________________________________________________________________________
Date: Sun, 7 Dec 2003 19:06:38 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
If you REALLY want a reference, output to film, which
you can be sure will be viewable, without ANY profile, or with a
built-in colour-checker pattern...Smithsonian says up to 100 years
for modern transparency films..
bfr
___________________________________________________________________________
Date: Sun, 7 Dec 2003 22:35:03 -0500
From: “Michael Demyan”
Subject: RE: RGB Numbers- for Eric (N9VJG)
Hi Eric:
Try opening the file with “Discard Embedded
Profile” to see the actual image in YOUR working space.
Michael C. Demyan
Fine Photography & Digital Graphic Design
www.mikedemyan.com
www.pbase.com/mdemyan
___________________________________________________________________________
Date: Sun, 7 Dec 2003 23:00:05 -0800
From: “Darren Bernaerdt”
Subject: re: RGB Numbers
David,
Having measured the spectral information of a D1x
sensor, I’m hoping you can
comment on the following:
When looking at the spectral response of a mid to high
end digital camera,
are there a significant number of colors that get
clipped by working in a
RGB space such as ColorMatch or sRGB? Although a larger
working RGB space
such as Adobe RGB may look attractive, are we really
gaining any meaningful
additional data?
Darren Bernaerdt
___________________________________________________________________________
Date: Mon, 8 Dec 2003 09:06:44 -0500
From: John Castronovo
Subject: Re: RGB Numbers
From: “Barry Rowland”
If you REALLY want a reference, output to film, which
you can be sure
will be viewable, without ANY profile, or with a
built-in
colour-checker pattern...Smithsonian says up to 100
years for modern
transparency films..
Without a doubt.
A large format transparency made on an LVT is a long
lasting, analog archive that contains all the color and sharpness of the
digital file, and it stores in less space than a CD. What’s not to
like?
john castronovo
tech photo & imaging
___________________________________________________________________________
Date: Mon, 8 Dec 2003 09:49:32 -0500
From: “Gerry Shamray”
Subject: RE: Digest Number 931
Hi everyone,
Each day, I always look forward to reading the posts
found here! I am curious on the constant debate of profiling and since
Photoshop 4 was recently brought up...BP-before profiling, we had just one
set of RGB numbers. I find the comments that these numbers have no meaning
today interesting. Why is that? AP-after profiling, the meaningless numbers
now have a meaning or, at least, a definition for interpretation for their
use. I follow that to a degree but I don’t understand specifically
why, if there is no profile, these original RGB numbers would have no
meaning? Why can’t, say, R-100, B-100, Y-100, mean the same thing? Is
it because now there are several different RGB spaces? What then, would be
the equivalent for Photoshop 4 RGBs?
Thanks,
Gerry Shamray
___________________________________________________________________________
Date: Mon, 08 Dec 2003 07:59:33 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/7/03 7:19 PM, N9VJG wrote:
I find your solution compelling. However, I’m
confused. I downloaded
the file and found an embedded ColormatchRGB
profile—not the custom
D1 input profile.
Correct, Both files where converted into one document
in ColorMatch. If the embedded profiles where the originals, you1d have a
heck of a time seeing them in a web browser.
Then I checked both images with the densitometer
tool and the numbers were quite different. Obviously,
the images look
different. What am I missing?
Two files with identical numbers but then converted
using two DIFFERENT input profiles into ColorMatch.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Mon, 08 Dec 2003 08:03:12 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/7/03 8:06 PM, Barry Rowland wrote:
If you REALLY want a reference, output to film, which
you can be sure
will be viewable, without ANY profile, or with a
built-in
colour-checker pattern...Smithsonian says up to 100
years for modern
transparency films..
And what happens in 120 years as the film fades? A
digital file can last forever and your film dupe is a poor quality dupe
since there is always a lot of degradation copying analog. The digital file
will be prefect 200 years from now as long as it1s copied whenever
necessary to the newer media.
And with that film in 120 years, what can we do with it
if no scanners exist to produce digital values from it? Film also fades
(unevenly) and it1s real hard to tell how much. It1 not like without
freezing the film it will remain identical color wise in 100 years as it
appears today.
The film has a gamut that1s probably nothing like the
original so where1s the match? Also what film? Fujichrome has a vastly
different 3look2 than Ektachrome. Seems like an awful lot of work (making a
film dupe) that1s full of problems.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Mon, 08 Dec 2003 09:40:05 -0600
From: Robert Perry
Subject: Re: Debate
On Dec 6, 2003, at 5:39 PM, Mike DeSantis wrote:
I have to agree with Aaron... Be passionate about
color, but keep your
integrity and character intact...
I second that.
Rob Perry
Western Producer Publ.
___________________________________________________________________________
Date: Mon, 8 Dec 2003 07:31:53 -0800
From: David Cardinal
Subject: RE: RGB Numbers
When looking at the spectral response of a mid to high
end
digital camera, are there a significant number of
colors that
get clipped by working in a RGB space such as
ColorMatch or
sRGB? Although a larger working RGB space such as Adobe
RGB
may look attractive, are we really gaining any
meaningful
additional data?
For the D1 and D1X (both of which were measured) and
the D1H which is similar to the D1X, the cameras have a larger gamut than
sRGB (so I personally never shoot into sRGB in the camera, but convert
later if needed).
The overall “size” of the gamut is similar
to Adobe RGB but not the same shape. If I get a chance I’ll try and
do an illustration.
I published a chart of the raw data (every 10nm) for
the D1 in The D1 Generation book, and for the D1X in the D00 & TDG
Update eBook. —David
___________________________________________________________________________
Date: Mon, 8 Dec 2003 08:07:05 -0800
From: Richard Chang
Subject: RGB Numbers
David Cardinal posted:
If someone wanted to save a “key” with the
Raw data, I’d personally save the
spectral response data (e.g. response to light of each
frequency) for the
camera sensor/filter. With that key plus the sensor
data it is possible to
reconstruct the image. Of course, I don’t know of
any camera company that
publishes that data. I’ve measured it for the
D1X, but it takes a bunch of
equipment & time. It’d be nice if it was
published the same way Kodak, Agfa
and Fuji publish their film response curves!
I am curious as to the specifics of response to light
of each frequency.
Can you define “each frequency”?
If I understand it correctly, spectral response is a
function of the illuminant used. The Lab folks prefer Illuminant C
which has a color temp in the neighborhood of 7000 degrees Kelvin.
Can you tell us how this spectral data should be assembled?
Richard Chang
___________________________________________________________________________
Date: Mon, 8 Dec 2003 08:10:30 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
Dear Andrew, et al...
Well, first point, I was talking about digital output,
not an analog dupe.
Point two, I also suggested inclusion of the
appropriate colour check chart
Point three - it’s more likely that there will be
scanning technology, and much better, in 100 years, than being able
to read a TIFF from a CD-ROM!
Point four, “the digital file will be perfect 200
years from now as long as”...
- as long as it’s copied to new media every 3-6
years
not because the media fails, but
because the media is overtaken by newer technology
- as long as the profile embedded makes any sense to an
end user
- as long as the file format is usable
how long before a PSD or
TIFF or JPEG is obsolete
- as long as no-one erases it accidentally
oops!
- as long as someone cares about archiving
“C-1187-v5-rgb.tif”
the film image is
immediately viewable, without any tech, beyond a light source and
eyeball, and thus has some intrinsic value to a viewer, and may be
evaluated instantly for archiving.
It really seems to me, in my naivete and innocence,
after only 25 years in the hard technology business, that there are
an awful lot of “as long as” conditions on digital
archiving...
Respectfully,
Barry Rowland
___________________________________________________________________________
Date: Mon, 08 Dec 2003 08:08:31 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/8/03 7:06 AM, john c. wrote:
Without a doubt.
A large format transparency made on an LVT is a long
lasting, analog archive
that contains all the color and sharpness of the
digital file, and it stores
in less space than a CD. What’s not to like?
Come on, it doesn1t contain all the info of the
original, it1s a 2nd generation and if the original came off a 13 stop
Betterlight scan back, you1re not going to get a fraction of the original
data. Even with a 1Ds I suspect you1ll lose tonal range from the original
capture and perhaps a good deal of color gamut that film can1t contain.
You1re also giving me something I don1t want that wasn1t in the original
(grain) assuming again the original came from a digital capture.
What1s not to like is a lot of data loss from the
original. It1s a dupe. A digital dupe but a dupe none the less. Also how
does going from a digital file to a piece of film eliminate all the profile
issues that some here are trying to avoid? We still need the right RGB
numbers for the LVT...
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Mon, 08 Dec 2003 09:38:57 -0700
From: Andrew Rodney
Subject: Re: Digest Number 931
on 12/8/03 7:49 AM, Gerry Shamray wrote:
Hi everyone,
Each day, I always look forward to reading the posts
found here! I am
curious on the constant debate of profiling and since
Photoshop 4 was
recently brought up...BP-before profiling, we had just
one set of RGB
numbers. I find the comments that these numbers have no
meaning today
interesting. Why is that?
PS4 and earlier and all non ICC savvy applications just
send the RGB numbers to the screen. In this context, the meaning is simply
what you see. But a HUGE problem is that display systems have to be
regularly calibrated (because they drift) and profiled other wise everyone
sees the same numbers differently which is simply chaos. PS4 and similar
insure that no two people are seeing the same numbers the same way. That1s
not how things work in Photoshop now (just the opposite).
We also had a nifty way of converting from RGB to CMYK
prior to using ICC profiles. As color theory goes, you have to always have
a definition of where the numbers are coming from in order to get resulting
numbers for output or any conversion for that matter. That1s as true with
proprietary conversions and ICC conversions. So the definition of RGB in
the old days was something known as 3Monitor Pref2 in Photoshop. It used
whatever file was supposed to represent the users display as the source
(and then formula to produce CMYK values from it). If two Photoshop users
took the same RGB file and converted on two different Mac1s to the same
CMYK recipe, they would both get different files (numbers) based on this
poor assumption of the numbers.
I don’t understand specifically why, if there
is no profile, these original RGB numbers would have no
meaning? Why can’t,
say, R-100, B-100, Y-100, mean the same thing?
RGB is a device dependant colorspace. Just like CMYK.
Take R-100, B-100, Y-100 in a square in Photoshop and assign different RGB
Spaces and you1ll see the appearance of the numbers change. You get to SEE
what the color SHOULD look like. You can1t do that without the color
architecture we have in Photoshop and similar smart color applications.
R-100, B-100, Y-100 is simply a recipe for a color. But it can1t tell us
what the color will look like.
Is it because now there are
several different RGB spaces? What then, would be the
equivalent for
Photoshop 4 RGBs?
There are thousands of RGB colorspaces. The four you
speak of are synthetic RGB spaces which always contain neutrals if R-G-B.
But these spaces have been defined and modified over the years. You can see
what 3Adobe RGB 19982 really is by going into Photoshop, picking it as your
RGB Working Space, then using the popup menu, go into 3Custom2 where you1ll
see a dialog that contains the DNA of this space (gamma, white point and
chromaticity values).
That being the case, even in the Photoshop 3 and
4 days, we had PressView display systems which COULD produce multiple
displays all matching (Barco as well). These were true 3reference
displays2. The colorspace of a PressView was ColorMatch RGB so even the few
of us back then that edited our files that way had a very easy and seamless
transition to Photoshop 5. We were working in a Quasi-Device Independent
RGB space years before it showed up in Photoshop. Short of that, if you
went back in a time machine and looked at the conditions of the various
displays running Photoshop, they1d be all over the map.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
___________________________________________________________________________
Date: Mon, 08 Dec 2003 12:24:37 -0500
From: Lee Clawson
Subject: Re: RGB Numbers
on 12/8/03 9:06 AM, john c. wrote:
A large format transparency made on an LVT is a long
lasting, analog archive
that contains all the color and sharpness of the
digital file, and it stores
in less space than a CD. What’s not to like?
The cost for each picture. Starting with a 4x5 LVT,
then the later cost of an inter-neg for printing. The task of finding a pro
color lab (even today), they’re disappearing quickly.
I was happy to store pictures on CD/DVD and then go
direct to film/paper via Durst Lambda or similar device.
Lee
___________________________________________________________________________
Date: Mon, 08 Dec 2003 18:02:10 +0000
From: Shangara Singh
Subject: Re: Digest Number 931
It was 8/12/03 4:38 pm, when Andrew Rodney wrote:
There are thousands of RGB colorspaces. The four you
speak of are synthetic
RGB spaces which always contain neutrals if R-G-B. But
these spaces have
been defined and modified over the years. You can see
what 3Adobe RGB 19982
really is by going into Photoshop, picking it as your
RGB Working Space,
then using the popup menu, go into 3Custom2 where
you1ll see a dialog that
contains the DNA of this space (gamma, white point and
chromaticity values).
If you are running Panther on the Mac, you can
double-click on an ICC profile file in the Library > ColorSync >
Profiles folder and see the color spaces graphically represented in the
ColorSync Utility. You can open two or more profiles to compare their color
spaces. There is also other info that you may find interesting.
—/ Shangara Singh.
___________________________________________________________________________
Date: Mon, 8 Dec 2003 09:44:55 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
As someone whose primary business is technology, I have
far less confidence in its longevity and reliability than many...in my
short span of years, I’ve seen 1/2” tape, 8” floppies,
5-1/4”, 3-1/2”, CD_ROM, DVD, DVD-x...
On Monday, December 8, 2003, at 08:53 AM, Andrew Rodney
wrote:
I’m aware it’s done digitally but analog
film is part of the process. I
started out shooting a 9 or 13 stop image with a good
chip and then I have
to introduce grain AND a big H&D curve into the
process for what?
Well, if you output to 70mm or 4x5 from ANY digital
camera you can name, the grain size will be insignificant compared to the
pixel size...and, after all, every colour pixel in a digital camera (not
scanner), is really NOT a colour pixel, but an algorithmically-derived
colour/lightness value. And, the H&D curve is analog, essentially
stepless, and readable on a densitometer to provide the
“profile” for that piece of film
Which looks a lot poorer than it should due to point
one above.
I thought that it should look just fine, given that we
are working in a colour-managed work flow...and, it’s purpose is to
provide the information necessary for any corrections to put the image back
into its “original” form...
You think? Scanning film? Read this month’s Wired
about Amazon and others
scanning books. I see in 10 years let alone 100 years
film will be about as
common and glass negs. Someone might be scanning them
inside some museum (if
all the stuff wasn’t scanned 20 prior).
Ah, but glass plates and negatives are _still_ here,
over a hundred years old, still printable and scannable. I have to say
that, as long as there are physical media carrying images and text, there
will be a need for scanners.
And you get that 3-6 years where? And if I end up doing
it every 6, so what?
I get these numbers from observation of the business...
how quickly have DVD’s taken over as a major storage medium from
CD-ROM? How many formats of DVD have we seen in the last 3 years?
The part that bothers me is “If I end up doing it
every 6 years”... what if it doesn’t get done?
And if it doesnt? The data is still there. The
alternative is to not
provide a profile which I think is silly. So 100 years
from now they can’t
find out how Photoshop CS ran? I’m not really
worried about it. Far more
likely the file is useful and filled with instructions
(ever hear of
Metadata?) than a piece of film. Of course go for that
one too.
Andrew, I do support profiles, they make sense to me; I
certainly did not suggest that no profile be embedded, merely that it may
not be readable...And, gee, what a surprise, I HAVE heard of Metadata!
I’m including it in the imaging database that I am working on, so I
HAVE to know about it, and, not to put too fine a point on it, have known
about it for some time...
That’s super easy to insure CAN’T happen.
Yes someone can accidentally toss
your only CD into a shredder. Not like someone
can’t scratch your film
(instant data loss).
Yep, but, in storage, in a sleeve...and what happens to
a scratched DVD?
If the image has value, someone will insure it’s
taken care of. If not, who
cares?
The point I was trying to make is that an image that
you pick up and look at is a little more readily-judged than a filename or
thumbnail...
There are no guarantees but you can use technology and
common backup sense
to limit the possibilities of total data loss. But if
the bombs fly and we
nuke the planet (or even the city you live in), the
images being lost will
be the least of your worries!
Most of us have seen where floppies have been replaced
by CD and that’s a
huge jump in a very short period of time.
As I pointed out earlier, that’s not even the
latest of the changes...
br
___________________________________________________________________________
Date: Mon, 08 Dec 2003 11:03:37 -0800
From: CitizenRay
Subject: Anyone considered checking color via LVT?
Anyone considered checking color via LVT transparency
film?
Does your scanner and/or monitor match the transparency
when imaged back to Ektachrome film?
Of course it’s seems expensive, but what
isn’t?
Just a quick survey,
-Stephen Ray
___________________________________________________________________________
Date: Mon, 8 Dec 2003 12:55:15 -0800
From: David Cardinal
Subject: RE: RGB Numbers
I am curious as to the specifics of response to light
of each frequency.
Can you define “each frequency”?
Sure. If you have a lot of patience, every nanometer in
the appropriate range would be ideal. That would be around 400 samples for
a D-SLR. When we did it we measured every 10nm, which was a lot quicker and
gave us what we needed.
If I understand it correctly, spectral response is a
function
of the illuminant used. The Lab folks prefer
Illuminant C
which has a color temp in the neighborhood of 7000
degrees
Kelvin. Can you tell us how this spectral data
should be assembled?
The trick about this approach is that you beam light at
precisely one frequency at a time into the camera. For example, 400nm, then
410nm, then 420nm, etc. You then measure the resulting values at the
sensors (e.g. the Raw data as measured by each “color” sensor
that is in the light).
So the illuminant is actually what you are using as the
input, one frequency at a time.
This process assumes the CCD is linear in response,
which they mostly are. If you wanted to be able to adjust for that as well,
you could repeat this experiment with differing intensities of light and
record all the data.
As to how to do this, it requires a bunch of special
purpose expensive lab equipment (or at least that is the only way I know to
do it). It is not practical for photographers to run off and do it, BUT at
least some camera companies do this and they have the numbers. So if the
industry wants a way to recreate the image 100 years from now, these
numbers are the key (or at least one possible key) to accurately unlocking
the Raw data.—David
___________________________________________________________________________
Date: Mon, 8 Dec 2003 20:21:42 -0000
From: “Bob Frost”
Subject: Re: RGB Numbers
Barry,
Just because some people may NEED film or plate
scanners doesn’t mean that there will be anyone MAKING them,
any more than they will be making 8” floppy drives to read
those old IBM DisplayWriter floppies I still have. They’ll all
be making brain scanners to send those images captured by our eyes
directly to our Epsons!
Bob Frost
___________________________________________________________________________
Date: Mon, 08 Dec 2003 21:42:43 -0000
From: “Roy Harrington”
Subject: Re: RGB Numbers
—- In colortheory@yahoogroups.com, Barry Rowland
wrote:
As someone whose primary business is technology, I have
far less
confidence in its longevity and reliability than
many...in my short
span of years, I’ve seen 1/2” tape,
8” floppies, 5-1/4”, 3-1/2”,
CD_ROM, DVD, DVD-x...
I totally agree with Barry. The number of digital
technologies that have come and gone is mind-boggling. I have
examples of pretty much all those and others — and
there’s no way to read any of the older stuff.
Ah, but glass plates and negatives are _still_ here,
over a hundred
years old, still printable and scannable. I have to say
that, as long
as there are physical media carrying images and text,
there will be a
need for scanners.
The great thing about the film images is that only the
initial creation was needed. No more intervention was ever needed
again. Finding a fifty-year-old film in some old closet or warehouse
can still yield useful images.
The part that bothers me is “If I end up doing it
every 6 years”...
what if it doesn’t get done?
Another good point, once you have one failure
it’s a complete loss. Whether its a human error, media failure,
technology obsolence there’s no “graceful
degradation” — I’d much rather have a faded image than no
image.
The trouble is the “person who cares” not
only has to care but has to be diligent “forever”.
“Value” is in the eyes of the beholder, what value is it to the
future generations.
Roy
___________________________________________________________________________
Date: Mon, 8 Dec 2003 22:10:57 -0500
From: John Castronovo
Subject: Re: RGB Numbers
The cost for each picture. Starting with a 4x5 LVT,
then the later cost of
an inter-neg for printing. The task of finding a pro
color lab (even today),
they’re disappearing quickly.
Cost wasn’t the question, rather how to archive
an important digital file.
I was happy to store pictures on CD/DVD and then go
direct to film/paper via
Durst Lambda or similar device.
. . .and this is free, I suppose, and available
anywhere but a pro color lab?
john c.
___________________________________________________________________________
Date: Mon, 8 Dec 2003 22:29:00 -0500
From: John Castronovo
Subject: Re: RGB Numbers
Andrew, I have a top of the line Betterlight back and
an LVT, and believe me, my 8x10 chrome from any digital file is a beautiful
thing to behold. Fully color managed and capable of holding a gigabyte of
data, a Velvia chrome has all the detail and color gamut it needs and then
some. At 8x10, grain isn’t an issue. Add a gray scale and color bar
with original values, and future generations will be able to assess the
degree of change.
And it’s not a dupe, it’s an original
digital output of unsurpassed quality. While it’s not the file
itself, it’s the most faithful expression of that file, and if all
the computers on earth die an early death, your grandchildren will still be
able to appreciate it because they’re analog too. That’s an
archive attribute worth considering.
john castronovo
tech photo & imaging
___________________________________________________________________________
Date: Mon, 8 Dec 2003 22:47:42 -0500
From: John Castronovo
Subject: Re: Anyone considered checking color via LVT?
From: “CitizenRay”
Does your scanner and/or monitor match the transparency
when imaged backto
Ektachrome film?
It can’t match unless the LVT output is profiled.
Then, what’s the point? It’s supposed to match if all the
profiles are done correctly.
If you’re asking if we can make a “digital
dupe” by drum scanning a chrome and then making an LVT chrome, the
answer is yes - and no. There are small differences, but it would take a
pro to notice or care. The biggest errors are in the scan (analog to
digital), not the LVT (back to analog).
john castronovo
tech photo & imaging
___________________________________________________________________________
Date: Mon, 8 Dec 2003 20:54:34 -0800
From: Richard Chang
Subject: RGB Numbers
David Cardinal wrote:
So the illuminant is actually what you are using as the
input, one frequency
at a time.
I must be missing the point here because if you
don’t shoot your pictures with the same illuminant you’re
calibrating the sensor with, what’s the point?
This process assumes the CCD is linear in response,
which they mostly are.
If you wanted to be able to adjust for that as well,
you could repeat this
experiment with differing intensities of light and
record all the data.
While the process assumes a linear response, I
don’t ever remember a good looking linear mapped image when printed
on a reflective substrate. We always remap, thereby inducing delta
error.
As to how to do this, it requires a bunch of special
purpose expensive lab
equipment (or at least that is the only way I know to
do it). It is not
practical for photographers to run off and do it, BUT
at least some camera
companies do this and they have the numbers. So if the
industry wants a way
to recreate the image 100 years from now, these numbers
are the key (or at
least one possible key) to accurately unlocking the Raw
data.—David
I’m having a hard time understanding how to apply
the spectral data from a test bench to a photograph that wasn’t made
with the test illuminant.
Richard Chang
___________________________________________________________________________
Date: Mon, 8 Dec 2003 21:33:33 -0800
From: David Cardinal
Subject: RE: RGB Numbers
The spectral response describes the camera’s
response to light. You could instead store a profile along with the image,
but then you are limited by today’s profiling software and
technology. Having the raw response data allows you to use the technology
of a future time to infer what was
captured.
From the original posting I inferred the question was
about retaining the most information about a raw image capture of an
arbitrary scene, so the illuminant may be unknown. In that case all we can
do is keep the raw sensor data & the information about the
sensor’s responsiveness. Sure, if you are attempting to archive a
physical photograph via image capture or you have a scene where you know
the illuminant then recording that information also would be great, but in
many cases photographers don’t have those options.
This is pretty far afield from the color list, so feel
free to email me, as I’m not sure I want to bog the list down with a
relatively arcane issue.—David
___________________________________________________________________________
Date: Mon, 8 Dec 2003 21:43:52 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
I, for one, would certainly like to have such
information available to me, for any camera system that I would use;
it’s equivalent to the sensitometry information for film.
Richard...the point is just that the calibration is
independent of any illumination source; if the sensor is fully-calibrated,
it’s easy to calibrate the effect of an illuminator on a subject, and
thereby produce the “system” composite spectral response. This
is really quite interesting, and potentially critical, knowledge, as many
illuminators (and some pigments and dyes, especially fluorescent materials)
have rather non-contiguous spectra, which cause a form of metamerism at the
sensor level.
If a sensor has a well-known response, and is linear,
you can map that accurately to any curve that you want, but that mapping is
simply a requirement of the display mechanism’s response; it’s
all about the output device and the viewer.
cheers,
br
___________________________________________________________________________
Date: Mon, 8 Dec 2003 21:50:47 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
David:
indeed, I think that this is quite appropriate for a
“color theory” list... As mentioned in my previous post,
if you have a well-”profiled” sensor, and a known
illuminator spectra, you have a system response characteristic, which
is really the ultimate form of a profile; no more than we expect from
the film that we shoot. How else would we determine (for film)
the correct filtration for 3400K or “cool white”? Most
folks probably leave this to “white balance” in a digital
camera/imager, which actually wastes a bit of the dynamic range of
the sensor. but, perhaps we digress...
cheers,
br
___________________________________________________________________________
Date: Tue, 09 Dec 2003 07:50:15 -0000
From:Stephen Marsh
Subject: Re: Digest Number 931
Andrew Rodney wrote:
That being the case, even in the Photoshop 3 and 4
days, we had PressView
display systems which COULD produce multiple displays
all matching (Barco as
well). These were true 3reference displays2. The
colorspace of a PressView
was ColorMatch RGB so even the few of us back then that
edited our files
that way had a very easy and seamless transition to
Photoshop 5. We were
working in a Quasi-Device Independent RGB space years
before it showed up in
Photoshop. Short of that, if you went back in a time
machine and looked at
the conditions of the various displays running
Photoshop, they1d be all over
the map.
Andrew, back in v4 and earlier - it was possible for
multiple versions of Photoshop to all be setup to the same RGB space, on
Mac or PC - I worked in at least two shops with this approach (Apple RGB is
the closest description to this default legacy Apple 13” display data
that was entered into monitor setup on all systems in the studio).
Are you saying that these multiple systems, all using
the same source description - ended up with different values in CMYK? I do
not remember this being the case.
On the Mac on v4, one had to make an effort to stop
ColorSync monitor profile taking over from the house standard chosen for
work instead of the monitor profile (Apple RGB).
So I too thought that I was ‘working in a
Quasi-Device Independent RGB space years before it showed up in
Photoshop’ - but I have been told that this was not so when I brought
this up a month or two back on the list.
Stephen Marsh.
___________________________________________________________________________
Date: Tue, 9 Dec 2003 08:11:52 EST
From: Dan Margulis
Subject: Re: Re: Digest Number 931
Stephen writes,
Andrew, back in v4 and earlier - it was possible for
multiple
versions of Photoshop to all be setup to the same RGB
space, on Mac
or PC - I worked in at least two shops with this
approach (Apple RGB
is the closest description to this default legacy Apple
13” display
data that was entered into monitor setup on all systems
in the
studio).
Correct. This is how every large user I was associated
with at that time did things.
Are you saying that these multiple systems, all using
the same source
description - ended up with different values in CMYK? I
do not remember
this being the case.
It wasn’t.
So I too thought that I was ‘working in a
Quasi-Device Independent RGB
space years before it showed up in Photoshop’ -
but I have been told
that this was not so when I brought this up a month or
two back on
the list.
Your initial thought was correct. Some people think
that “Device-Dependent” and “Dependent on a Nonexistent
Device” are wildly different concepts. In the respect of uniformity
of conversions, the problem that v.5 purported to solve never really
existed.
Dan Margulis
___________________________________________________________________________
Date: Tue, 09 Dec 2003 09:50:44 -0500
From: Lee Clawson
Subject: Re: Anyone considered checking color via LVT?
Does your scanner and/or monitor match the transparency
when imaged back to
Ektachrome film?
Stephen,
Color match with monitor to (LVT) Ektachrome trans was
good. If anything, it was what I’d see in later prints, slightly dark
3/4 tones. I’d always include color and grayscale control patches
along one edge.
Lee
___________________________________________________________________________
Date: Tue, 09 Dec 2003 08:17:20 -0700
From: Andrew Rodney
Subject: Re: Re: Digest Number 931
on 12/9/03 12:50 AM, Stephen Marsh wrote:
Andrew, back in v4 and earlier - it was possible for
multiple
versions of Photoshop to all be setup to the same RGB
space, on Mac
or PC - I worked in at least two shops with this
approach (Apple RGB
is the closest description to this default legacy Apple
13” display
data that was entered into monitor setup on all systems
in the
studio).
Problems. IF the display wasn1t calibrated to exactly
that aimpoint, what you saw wasn1t accurate. You could share multiple
Monitor Preference files with multiple users. Again, Photoshop used that
info to do the CMYK to RGB conversions to the screen. If the displays and
preference didn1t exactly match (and 99 times out of 100 they did not), the
preview was wrong.
Are you saying that these multiple systems, all using
the same source
description - ended up with different values in CMYK? I
do not remember
this being the case.
IF they used different monitor preference files yes. If
they didn1t use different files, then the files had to describe the numbers
the display system was producing (easy with a PressView or Barco which
could physically adjust the display), nearly impossible with all others who
simply plugged in a display system and went to work in Photoshop.
On the Mac on v4, one had to make an effort to stop
ColorSync monitor
profile taking over from the house standard chosen for
work instead
of the monitor profile (Apple RGB).
Which would allow identical conversions and incorrect
previews for CMYK (unless you had PressView/Barco like systems).
So I too thought that I was ‘working in a
Quasi-Device Independent RGB
space years before it showed up in Photoshop’ -
but I have been told
that this was not so when I brought this up a month or
two back on
the list.
We were. I was. I was using a PressView and my
Quasi-Device Independent space was ColorMatch RGB since that1s what that
display system created (and built a custom monitor Preference from). But
anyone else who gave me files? Who knows. And I was limited by the gamut of
ColorMatch RGB. I had no options to work in a bigger or smaller editing
space. I also had to deal with Photoshop1s arcane method of doing any
colorspace conversions, had no soft proof and a really crude out of gamut
indicator (which still survives today and is basically useless).
on 12/9/03 6:11 AM, Dan Margulis wrote:
Your initial thought was correct. Some people think
that “Device-Dependent”
and “Dependent on a Nonexistent Device” are
wildly different concepts. In the
respect of uniformity of conversions, the problem that
v.5 purported to solve
never really existed.
Users who simply had no means of calibrating their
displays (and regularly) had a default, out of the box monitor preference
which was about as accurate as suggesting all files are really in sRGB. If
they hooked up their displays and used this preference, they pretty much
guaranteed that what they saw (especially in CMYK) was wrong. Photoshop
can1t send CMYK to the screen, an RGB conversion always goes on and some
piece of data is being used to do this. In PS4 and earlier, it was usually
wrong unless some calibrationist went to the effort to calibrate and create
what was at the time our profile (Monitor preference) file.
Photoshop 5 changed this all by divorcing what the
numbers in our files where and the display. We got Working (Editing) spaces
which were not at all attached to the behavior (calibrated or not) of our
displays which makes a great deal of sense. You don1t have to limit the
editing based on the kinks in a display system and you can insure a huge
number of users can edit their numbers and see them the same way no matter
what platform they were on. Speaking of which, imagine the chaos of having
Mac and PC users both looking at numbers, both being described by a monitor
preference that is based on their OS gamma (1.8 and 2.2) and then imagine
that the vast majority are not even calibrated to any standard. Talk about
a mess. That1s completely gone today with modern image editors (which there
are plenty of besides Photoshop that operate just like Photoshop).
Device on a non Nonexistent device isn1t at all a
problem. There isn1t really a device on the planet that behaves like Adobe
RGB or sRGB (the closest would be a display since that1s how they are
based). LAB, which Dan loves to promote is based on a Nonexistent
device (and it1s device independent since no device can possibly be
created that could operate like this TOTALLY SYNTHETIC device).
Andrew Rodney
http://www.imagingrevue.com
___________________________________________________________________________
Date: Tue, 09 Dec 2003 11:23:44 -0500
From: Lee Clawson
Subject: Re: RGB Numbers
John,
If the film exists I tell our clients to keep it, the
raw capture and the processed image.
After you make the 8x10 trans what do you do to archive
the digital file ???
Lee
___________________________________________________________________________
Date: Tue, 09 Dec 2003 08:17:13 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/8/03 8:29 PM, john c. wrote:
Andrew, I have a top of the line Betterlight back and
an LVT, and believe
me, my 8x10 chrome from any digital file is a beautiful
thing to behold.
I1m sure they are but you1ve still got grain and a BIG
H&D curve not in the Betterlight capture and something I don1t want
added to my digital images (from digital capture).
Fully color managed and capable of holding a gigabyte
of data, a Velvia
chrome has all the detail and color gamut it needs and
then some.
You1ve got the Velvia gamut but the Betterlight? I
doubt out. Plus what1s the cost of that sheet of 8x10 plus processing? Not
even close to the cost of even a DVD let alone a CD (or several CD copies.
You may have the loveliest LVT on earth but don1t tell
my you didn1t introduce all kinds of non image data (and lost data) going
from the Betterlight to the piece of film which BTW I assume some one has
to scan some day again since we are so worried about the digital file?
At 8x10, grain isn’t an issue.
Are you now telling me there is NO GRAIN in that film?
I hope not.
And it’s not a dupe, it’s an original
digital output of unsurpassed quality.
Unsurpassed quality of a piece of film of a digital
file, not the file itself. And IF I want to make a huge print on a
Lightjet, what1s going to give me better quality, going from the original
digital file or your digital/analog dupe?
While it’s not the file itself, it’s the
most faithful expression of that
file, and if all the computers on earth die an early
death, your
grandchildren will still be able to appreciate it
because they’re analog
too. That’s an archive attribute worth
considering.
It1s an awful silly way to back up what is really just
a set of numbers. Those numbers can be regenerated any number of times to
any number of locations and media and be perfect clones of the original
(which was a set of number from a digital camera). You1re copy is just that
and it1s NOT a faithful copy of the original. The only faithful copy of a
set of numbers is an identical set of numbers. You1re dupe may be a very
useful product to have, no argument but in no way is it a faithful copy
(not even close) to a file that began inside a digital capture device as
just numbers. You have to convert the data to an output profile just to
print it as you1ve admitted. That alone is alteration from the original.
If you’re asking if we can make a “digital
dupe” by drum scanning a chrome
and then making an LVT chrome, the answer is yes - and
no. There are small
differences, but it would take a pro to notice or care.
Well then there ARE differences and we can notice them.
Thanks!
The biggest errors
are in the scan (analog to digital), not the LVT (back
to analog).
Errors, analog? You1ve just made my point about this
process.
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Tue, 9 Dec 2003 11:40:23 -0800
From: Richard Chang
Subject: RGB Numbers
Barry Rowland wrote:
I, for one, would certainly like to have such
information available to
me, for any camera system that I would use; it’s
equivalent to the
sensitometry information for film.
Film sensitometery info is very general, specifically
because (for color film) the organic dyes from lot to lot aren’t
consistent (remember the numbers on the end of the film box?) and the
soup you mix up isn’t consistent either (tell me your lab
doesn’t replenish their soup). Compared to calibrating a digital
sensor, film sensitometery is a joke. Remember crossovers?, I’ve
never seen a color film plot without one. We did film sensitometery
because that’s the best we had at the time and because it seemed the
best method of characterizing film behavior.
Richard...the point is just that the calibration is
independent of any
illumination source; if the sensor is fully-calibrated,
it’s easy to
calibrate the effect of an illuminator on a subject,
and thereby
produce the “system” composite spectral
response. This is really quite
interesting, and potentially critical, knowledge, as
many illuminators
(and some pigments and dyes, especially fluorescent
materials) have
rather non-contiguous spectra, which cause a form of
metamerism at the
sensor level.
I don’t believe that the calibration is
independent of the illumination source. If you’re talking about
tonality, there’s no point in a nanometer specific calibration.
If you’re talking about chromaticity, chromaticity is specific
to the color of the light used to plot the calibration. Shoot with a
different color light source and your calibration with the namometer
specific illuminant is no longer valid. If you remember filter
theory, the color aborbed is specific to the color you’re putting
through the filter.
Regarding the ease of calibrating the effect of an
illuminant on a subject, thereby producing systemic composite spectral
response. Can you tell me how this is done? Feel free to
contact me off-list.
If a sensor has a well-known response, and is linear,
you can map that
accurately to any curve that you want, but that mapping
is simply a
requirement of the display mechanism’s response;
it’s all about the
output device and the viewer.
Actually, you can’t map accurately. Mapping
is one of the sources of delta-E. If you want great delta-E response,
don’t remap. The bigger the remap, the bigger the delta-E.
The problem with the whole calibration process is that just
processing, or having access to the numbers, doesn’t guarentee a good
rendering, although it often reduces some kinds of corrections.
Taking each individual image through a process of craftsmanship is
what makes a good rendering, which is what I thought this list is supposed
to be all about.
Richard Chang
___________________________________________________________________________
Date: Tue, 9 Dec 2003 12:46:45 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
On Tuesday, December 9, 2003, at 11:40 AM, Richard
Chang wrote:
I don’t believe that the calibration is
independent of the illumination
source.
the “illumination source” is a
monochromator, not an illuminant
If you remember filter theory, the
color absorbed is specific to the color you’re
putting through the
filter.
the colour absorbed doesn’t have anything at all
to do with the “color you’re putting through”... a filter
simply transmits, absorbs or reflects specific wavelengths; it has NO
dependence on the light going through it.
but, no need to believe _anything_ that I say....
not an “expert”
br
___________________________________________________________________________
Date: Tue, 9 Dec 2003 12:30:27 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
Dear Richard Chang,
who wrote, and I respectfully respond:
Taking each individual image through a process of
craftsmanship is what makes a good rendering, which is
what I thought this
list is supposed to be all about.
I seem to be confused... isn’t the title of the
list “color theory”?
I don’t believe that the calibration is
independent of the illumination
source.
Believe what you will, or not...
Actually, you can’t map accurately. Mapping
is one of the sources of
delta-E. If you want great delta-E response,
don’t remap.
Really?
If you remember filter theory,
gee, what’s that? ...I do seem to remember
something about Bayer matrices, silicon photo response, de-mosaicing
algorithms, sensor-induced metamerism, dark current, anti-aliasing filters,
system MTF... but filter theory?
May I suggest that you just aren’t
“getting” the whole issue of a calibrated sensor, as
independent from the subject reflectance and the illuminator? If not, all
the discussion of Delta-E and chromaticity coordinates is just an exercise
in futility...
cheers,
br
___________________________________________________________________________
Date: Tue, 9 Dec 2003 22:40:03 -0700
From: Chris Murphy
Subject: Re: RGB Numbers
On Dec 8, 2003, at 9:10 AM, Barry Rowland wrote:
Point three - it’s more likely that there will be
scanning technology,
and much better, in 100 years, than being able to read
a TIFF from a
CD-ROM!
I do not think this is a particularly good assumption.
If an image is so important to you, you need a 100 year strategy for it, it
makes sense to me that you would output to film and you’d also have a
digital archive. And the digital archive is updated to keep up with
technology. There will always be bridge technologies to move today’s
file formats and profiles, to the new formats and profiles. And if there
isn’t, that means something really bad happened and your image being
usable 100 years from now is the least of your problems.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Tue, 9 Dec 2003 22:33:40 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
Chris:
Sure enough, I didn’t suggest that you _would
not_ make a digital backup, I merely made the modest proposal that
the film “backup” would be less prone to technology
“slip”, and requires almost nothing in the way of
transferring files, converting files, converting formats...in short,
that it’s actually more reliable and trouble-free.
It appeared that you disagreed with my point
it’s more likely that there will be scanning
technology,
and much better, in 100 years, than being able to read
a TIFF from a
CD-ROM!
To that, I say: See how many places you can get a 128k
8 inch floppy read these days, after less than 25 years since they
were extant...
Every time the file is converted or transferred is a
possible step that could cause a mistranslation, as an example, and
is certainly a step that _must_ be performed by someone, or some
thing... if it’s not done, all bets are off!
I did not say that film was cheaper, or more accurate,
just more reliable, and more likely to survive in a viewable,
reproducible state.
To go even further, we could output silver-based
b&w separations, along with appropriate step wedges and
targets...
but I think that most of those who care have already
grasped the basic argument.
I think that I’ve raised enough dust for this
week...
br
___________________________________________________________________________
Date: Wed, 10 Dec 2003 10:54:35 -0000
From:Stephen Marsh
Subject: Re: Digest Number 931
Thanks for the confirmation on the v4 behaviour Andrew.
I thought I had that part right.
Although I am still confused by the statements
previously made on the list when this came up a while back (they may not
have been your statements, I can’t recall) - that changing the
monitor setup did not affect the visual display. What was the point, apart
from mode conversions (or was that it)?
Stephen Marsh.
___________________________________________________________________________
Date: Wed, 10 Dec 2003 00:00:48 -0800
From: Richard Chang
Subject: Re: RGB Numbers
Barry Rowland wrote:
May I suggest that you just aren’t
“getting” the whole issue of a
calibrated sensor, as independent from the subject
reflectance and the
illuminator? If not, all the discussion of Delta-E and
chromaticity
coordinates is just an exercise in futility...
and,
I do seem to remember something about Bayer
matrices, silicon photo response, de-mosaicing
algorithms,
sensor-induced metamerism, dark current, anti-aliasing
filters, system
MTF... but filter theory?
Perhaps I don’t “get it”, but
that’s OK by me. I also don’t get sensor induced
metamerism; as I understand it, metamerism is a problem where colored
reflectances don’t properly relate to changes in lighting conditions.
I don’t understand how a sensor can “induce”
rendering colorants or lighting conditions to misbehave. I can
understand how sensor colorants and interopolation methodology can fail to
accurately record colors we can see.
I seem to be confused... isn’t the title of the
list “color theory”?
When I took Dan’s Color Theory I class, we
covered craftsmanship with regard to the theory of how files are affected
by specific controls commonly used by professional color separation
experts. Perhaps that class was more about the theory of color
manipulation as opposed to the theory of calibration and profile
manufacture.
the colour absorbed doesn’t have anything at all
to do with the “color
you’re putting through”... a filter simply
transmits, absorbs or
reflects specific wavelengths; it has NO dependence on
the light going
through it
I aparently don’t get filter function either,
because I learned that filters absorb specific wavelengths.
There’s little point in absorbing a wavelength that
doesn’t exist in the light one’s attempting to filter, which
makes me believe that the color of the illuminant is very relative to the
filtering you’re attempting to do.
I’ll assume that we’ll agree to disagree on
these subjects, there’s really no need to further an additional
debate on this list.
Best Regards,
Richard Chang
___________________________________________________________________________
Date: Wed, 10 Dec 2003 07:32:34 -0800
From: David Cardinal
Subject: RE: RGB Numbers
Perhaps I don’t “get it”, but
that’s OK by me. I also don’t
get sensor induced metamerism; as I understand it,
metamerism
is a problem where colored reflectances don’t
properly relate
to changes in lighting conditions. I don’t
understand how a
sensor can “induce” rendering colorants or
lighting
conditions to misbehave. I can understand how
sensor
colorants and interopolation methodology can fail to
accurately record colors we can see.
Richard—An RGB sensor can have metamerisms
independent of lighting. Since it is only measuring 3 values instead of the
entire spectrum, two different colors can measure the same, even under
identical lighting (filters are of course picked to minimize this problem).
I often wonder whether it will ever be practical to have a full
spectrophotometer capability in cameras. Sony has started adding a 4th
color, although I don’t know if there have been any tests yet on how
much it solves this problem.—David Cardinal
___________________________________________________________________________
Date: Wed, 10 Dec 2003 08:11:31 -0700
From: Andrew Rodney
Subject: Re: Re: Digest Number 931
on 12/10/03 3:54 AM, Stephen Marsh wrote:
that changing the monitor setup did not
affect the visual display. What was the point, apart
from mode
conversions (or was that it)?
For CMYK, yes of course. The CMYK to RGB Conversion (to
screen OR to a file) is based on the old monitor preference. For RGB, no,
it1s sent directly to screen (like most of our present day stupid web
browsers).
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Wed, 10 Dec 2003 10:00:32 -0600
From: Ron Bean
Subject: Re: RGB Numbers
Barry Rowland writes:
See how many places you can get a 128k 8 inch floppy
read these days, after less than 25 years since they
were extant...
That’s a bad example, because very few people had
8 inch floppy drives in the first place. By the time small computers became
common, they all had 5.25” floppies (which I can still read BTW), and
even those were nowhere near as common as computers with CD-ROM drives are
now.
Similarly, it’s hard to find 8mm movie
projectors, in part, because that format was never anywhere near as popular
as VHS video tape is now (some of the current camcorder tape formats might
fall into the same category as 8mm film).
A better example might be reading a 78 rpm record,
which was a very popular format before 1948 (my parents had stacks of
them). Reading a vinyl LP is no sweat (partly because they still
haven’t completely disappeared).
A search for “9 track tape” shows several
companies still selling drives for that format. A search for “16mm
film projector” also turns up quite a few (is that format still in
use?).
The wildcard here is that CD drives tend to wear out
quickly, but most DVD drives can read CDs (and this is likely to be true
until they change the physical size of the disk).
___________________________________________________________________________
Date: Wed, 10 Dec 2003 08:21:26 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
Good explanation, David!
Current research is suggesting that seven
carefully-selected filters are the minimum for
“museum-quality” imaging, and that sixteen filters give a
good enough result that it’s possible to simulate viewing
paintings under different illuminants.
cheers,
Barry
___________________________________________________________________________
Date: Wed, 10 Dec 2003 15:58:44 -0500
From: Frank ODonnell
Subject: Re: RGB Numbers
On Wednesday, December 10, 2003, at 11:00 AM, Ron
Bean wrote:
See how many places you can get a 128k 8 inch floppy
read these days, after less than 25 years since they
were extant...
Googling 128k 8 inch floppy, first on the list was:
Which shows a guy who runs his disk.
___________________________________________________________________________
Date: Wed, 10 Dec 2003 16:27:33 -0700
From: Chris Murphy
Subject: Re: RGB Numbers
On Dec 9, 2003, at 11:33 PM, Barry Rowland wrote:
Chris:
Sure enough, I didn’t suggest that you _would
not_ make a digital
backup, I merely made the modest proposal that the film
“backup” would
be less prone to technology “slip”, and
requires almost nothing in the
way of transferring files, converting files, converting
formats...in
short, that it’s actually more reliable and
trouble-free.
I disagree that film is less prone to slip. You would
have to rescan it, and therefore create something that is at least one, if
not two steps, removed from the original. While having to constantly keep
up with technology, your digital duplicates, moved to different file
formats and different media, are all exact copies.
To that, I say: See how many places you can get a 128k
8 inch floppy
read these days, after less than 25 years since they
were extant...
You are proposing waiting until today to have converted
that 128k floppy? There have been countless opportunities to get the data
to something current. Anyone suggesting that they stick a CD into a closet
and then in 100 years figure out what to do with it does not have a digital
archiving strategy. Once the writing is on the wall that CD’s
shouldn’t be used for long term archiving (i.e. now), consideration
for moving them to the next perceived media should begin in ernest.
Probably the next most logical media is DVD. But heck even using a hard
drive and sticking it up on a shelf is practical (use a hard drive and use
DVD so you have at least two copies).
Every time the file is converted or transferred is a
possible step that
could cause a mistranslation, as an example, and is
certainly a step
that _must_ be performed by someone, or some thing...
if it’s not done,
all bets are off!
I can remember the last time I had such a problem. It
was with a 3.5 inch floppy. Although I have heard of people having problems
with CD’s not being readable after being stored out on their desk, or
having been written on with indelible marker, I think we’re at a
point that reasonable precautions can be made to eliminate losing
your digital archive. That’s why you make at least two, using
two different kinds of media.
I did not say that film was cheaper, or more accurate,
just more
reliable, and more likely to survive in a viewable,
reproducible
state.
Well, it’s a lot bulkier, and it has special
storage requirements to last that long. So I think it’s not necessary
better. I think it’s just a different way of doing it. I personally
would consider the film backup the last resort if my two digital archives
somehow were toasted. I’d rather use the digital originals.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
___________________________________________________________________________
Date: Thu, 11 Dec 2003 13:55:13 -0000
From: “Bob Frost”
Subject: Re: RGB Numbers
Ron,
I’ve just bought a new hifi record deck that
plays 78’s as well as 45’s and 33’s. Made in Germany. So
I can now play my old 78’s and record them to DVD. If there is enough
demand for something, someone will make it.
Bob Frost.
___________________________________________________________________________
Date: Thu, 11 Dec 2003 13:32:28 -0800
From: John Wickham
Subject: Re: RGB Numbers
on Wed Dec 10 Barry Rowland wrote:
Current research is suggesting that seven
carefully-selected filters
are the minimum for “museum-quality”
imaging, and that sixteen filters
give a good enough result that it’s possible to
simulate viewing
paintings under different illuminants.
Barry
could you please explain,” museum-quality imaging
“ and “ simulate viewing paintings under different
illuminants “
as i am interested in the reproduction of
paintings
thank you, John Wickham Premier
Graphics Ltd
________________________________________________________________________
Message: 14
Date: Thu, 11 Dec 2003 21:32:17 -0600
From: “Howard Smith”
Subject: Re: Debate
From: Aaron Hill
It is amazing to read so much passion and
intensity about color. This is
both good and bad. I think we should all
remember that, although knowledge
and understanding are important, it is
relatively unimportant in the scheme
of things. Obviously some of these arguments
have become personal. Please
just report the facts, and then the reader can
make a judgment for himself.
Aaron, maybe it’s the advantage of age,
and maybe I’m just flat wrong, but several folks here may be
misinterpreting the underlying message in some of these heated posts.
Most of us know that Photoshop is a very individualistic sort of
program, permitting countless ways of achieving basically the same final
result.
(For those more proficient with English than I
am, maybe “individualistic” wasn’t used
correctly...please, have mercy!)
Most of these heated posts appear to be
expressions of the intense creative natures of the contributors rather than
being anything truly involving ill will. We all learn a lot here, and
we have a chance to express our own strong feelings on the
“best” way to do something. There is no best way, only
different ways. I have strong feelings on the decided advantages of
CMYK while others have even stronger feelings about the decided advantages
of RGB. You know what? I tried some of these objectionable
ideas and found they really worked surprisingly well. The only
serious mistake any of us can make is to believe that we have discovered
the holy grail of color correction.
Being anxious to learn as much as possible, my
own biased feeling is that almost all of these posts are informative and
usually good fun. Even the harshest complaints have been educational
on many an occasion. In fact one post, criticizing one or my own
posts, proved to be very helpful. While the wording was a bit
inflammatory, the critic was absolutely right! And I learned
something new.
So fire away, folks! This is the best
education I’ve had in years.
Howard Smith
___________________________________________________________________________
Date: Fri, 12 Dec 2003 08:23:37 -0400
(AST)
From: “Ellie Kennard”
Subject: Re: Debate
Hear! Hear! (While checking up on how to spell this, I
found that it is an abbreviation for “hear, all ye good people, hear
what this brilliant and eloquent speaker has to say!” which fits the
bill.)
Constantly learning from all postings in one way or
another,
Ellie
___________________________________________________________________________
Date: Sat, 13 Dec 2003 14:53:17 -0500
From: John Castronovo
Subject: Re: RGB Numbers
The following quote was snipped from a reply made on
the BetterLight group by Mike Collette who is the engineer behind their
scan backs:
—————-
Under optimum exposure conditions (short Line Time and
low ISO settings), your scan back is capable of 10 or 11 f-stops of dynamic
range, which should handle most photographic negatives OK (some X-ray films
have densities beyond 4.0, which makes them very difficult to scan with
almost anything).
—————-
From this I conclude that the scan back is closer to
the range of film than you might suppose.
Also, as you know, digital files are nothing but
numbers that need interpretation in some analog way to be an image. We HAVE
to go analog to see the picture, so now I ask how that is done best. A
monitor doesn’t do it, and reflective art leaves much to be desired
to mimic real life. I suggest that an LVT transparency provides the
greatest brightness range and gamut of all the analog choices - so it makes
the best expression of the file and a very convenient archive of the file.
It doesn’t replace the file. The minimal grain in an 8x10 Velvia is a
small price to pay and only important in enormous reproductions where the
original pixel data will be a factor before the grain will. The only thing
better I can think of would be a large format Duraclear made on a Lightjet
(hmmm).
As for the gamut, unless you’re archiving 16 bit
files, you’re reducing nature to 256 levels of RGB color anyway. If I
linearize and color manage my LVT output to place all of these 256 levels
on the film, haven’t I captured all the available data?
I appreciate your comments, Andrew, and I usually agree
with you. This is an area where I have much personal practical experience,
but I think that there is a philosophical question here too. I don’t
know about anyone else, but I can’t see numbers. I want a tangible
artifact as an archive as well as the numbers. On the other hand, it would
be reasonable to ask for the file as a backup to a digital work of art that
one has purchased, and museum curators are becoming aware of this.
There’s a need for both.
john castronovo
tech photo & imaging
___________________________________________________________________________
Date: Sat, 13 Dec 2003 17:06:42 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/13/03 12:53 PM, john c. wrote:
Also, as you know, digital files are nothing but
numbers that need
interpretation in some analog way to be an image. We
HAVE to go analog to
see the picture
They can be viewed on any number of digital displays
and never going analog. This might be the predominate way we view images in
the future, I1m not sure. I think cutting down trees and pouring on ink
might not be the best way to visually communicate in the future. But today
I still get pretty good technology for archiving what is just a big pile of
numbers that can produce a picture somewhere.
As for the gamut, unless you’re archiving 16 bit
files, you’re reducing
nature to 256 levels of RGB color anyway.
Archive the RAW and high bit original files. Space
isn1t really an issue.
If I linearize and color manage my
LVT output to place all of these 256 levels on the
film, haven’t I captured
all the available data?
Nope. And you1ve added stuff I don1t want like grain.
I appreciate your comments, Andrew, and I usually agree
with you. This is an
area where I have much personal practical experience,
but I think that there
is a philosophical question here too.
I have no problem with LVT work. I1ve had some done 13
years ago at a time where it was the only viable option for output. But
it1s hardly high on my list of methods of archiving digital data!
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Sat, 13 Dec 2003 17:37:30 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
Andrew:
I don’t know of ANY “digital”
displays...if it gets to our eyes, it seems to me that it must have been
converted to analog somewhere along the way! And, it got there
through CLUT’s, Gamma adjustment, conversion to an electron beam,
conversion from electrons to photons...
___________________________________________________________________________
Date: Sun, 14 Dec 2003 08:31:41 -0500
From: John Castronovo
Subject: Re: RGB Numbers
From: “Barry Rowland”
I don’t know of ANY “digital”
displays...if it gets to our eyes, it
seems to me that it must have been converted to analog
somewhere along
the way! And, it got there through CLUT’s,
Gamma adjustment,
conversion to an electron beam, conversion from
electrons to photons...
Horrors! You mean that all that stuff is messing with
my pure numbers?
john castronovo
___________________________________________________________________________
Date: Mon, 15 Dec 2003 11:23:48 -0500
From: Lee Clawson
Subject: Re: RGB Numbers
John,
I still don’t get it.
What I understand is that you’ll save all the
digital files and in addition make one formatted for an 8bit 8x10
transparency (at approximately $135 each).
In 50 years, at an exhibit of these photos, I’ll
be looking at 8x10 transparencies mounted in a light box.
Lee
___________________________________________________________________________
Date: Mon, 15 Dec 2003 14:31:38 -0500
From: Terry Wyse
Subject: Re: RGB Numbers
I’m surprised that nobody has suggested archiving
a 16bit LAB file for “posterity”. No embedded profiles to worry
about and an almost totally unambiguous interpretation of the image for the
foreseeable future.
So, long after Dan has convinced the world that
profiles are responsible for various cancers and early hair loss (I can
attest to that) and they’ve subsequently been obliterated from the
face of the earth, your “unambiguous” LAB file will still
likely be readable.
That was a joke Dan, along with the reference to 16bit
(WHAT was I thinking?!)
;-)
Cheers,
Terry
—
__________________________________
WyseConsul
Color Management Consulting
v 704.843.0858
__________________________________
___________________________________________________________________________
Date: Mon, 15 Dec 2003 16:34:49 -0700
From: Andrew Rodney
Subject: Re: RGB Numbers
on 12/15/03 12:31 PM, Terry Wyse wrote:
I’m surprised that nobody has suggested archiving
a 16bit LAB file for
“posterity”.
I don1t know of any device that captures 16 bit LAB.
There are some high bit scanners that will convert from whatever source
profile that describes it1s RGB to LAB but then you can do that now in
Photoshop. The only thing you gain is a file that is (color-wise) self
described (being LAB).
Andrew Rodney
http://www.imagingrevue.com/
___________________________________________________________________________
Date: Tue, 16 Dec 2003 00:26:00 -0000
From:Stephen Marsh
Subject: Re: RGB Numbers
—- Terry Wyse wrote:
I’m surprised that nobody has suggested archiving
a 16bit LAB file for
“posterity”.
Probably because those that are seriously into the high
bit workflows often shun ICC LAB mode. With more than 8 bpc of data they
often feel more happy about it - but not as happy as using a well behaved
RGB working space. Some folk would jump through countelss hoops to save a
trip to LAB, which is good in general principle although not so good if you
need quick and easy solutions to some tricky colour correction and
retouching situations.
No embedded profiles to worry about and an almost
totally
unambiguous interpretation of the image for the
foreseeable future.
As long as the reading app knows what LAB is and the
type of ICC LAB Photoshop was using.
I think the time has been and gone for this concept -
v4 or earlier would have been great, I think the concept of a LAB file is
workable for transport to unknown users - but just like ICC tagged files,
one has to put some faith in the next person and they may screw the LAB
file up in some unknown or unpredictable way.
So, long after Dan has convinced the world that
profiles are responsible for
various cancers and early hair loss (I can attest to
that) and they’ve
subsequently been obliterated from the face of the
earth, your “unambiguous”
LAB file will still likely be readable.
Depends on the app.
That was a joke Dan, along with the reference to 16bit
(WHAT was I
thinking?!)
Not sure Terry, perhaps the question should be -
“what was the devil on your shoulder thinking?”
Stephen Marsh
___________________________________________________________________________
Date: Mon, 15 Dec 2003 22:03:18 -0500
From: Terry Wyse
Subject: Re: Re: RGB Numbers
on 12/15/03 7:26 PM, Stephen Marsh wrote:
Not sure Terry, perhaps the question should be -
“what was the devil on your
shoulder thinking?”
A college of mine mentioned that I just MIGHT have too
much time on my hands this week. Probably true. In light of some of the
rankor I’d been hearing for the last few weeks, I thought a little
calibrationist levity was in order. Or not. Anyway, I promise not to take
that comedy BIT on the road anytime soon (sometimes I slay me).
Terry “Give up being a comedian and keep your day
job” Wyse
___________________________________________________________________________
Date: Tue, 16 Dec 2003 07:59:06 EST
From: Dan Margulis
Subject: Re: RGB Numbers
So, long after Dan has convinced the world that
profiles are responsible for
various cancers and early hair loss (I can attest to
that) and they’ve
subsequently been obliterated from the face of the
earth...
Ah, but they will live on in history, like the Edsel,
or Marshal MacMahon’s tactics in the Franco-Prussian war, or the
design team of the Tacoma Narrows Bridge. <g>
...your “unambiguous” LAB file will still
likely be readable.
Unlikely.
Seated in my beach chair, doing my best to stimulate
the Puerto Rican economy by excessive consumption of Barrilito Three-Star,
the best rum in the world, I must remark that this thread is about the most
fatuous series of posts I’ve seen since Andrew stopped lecturing us
on how embedded CMYK profiles were the wave of the future and resistance is
futile.
If the question is, what is the single form of storage
that is most likely to be salvageable in a hundred years, I completely
agree with John Castronovo that it’s an 8x10 transparency, however,
his argument with the others is moot. This is an extremely expensive way of
doing things. To do it, you have to be very wealthy, very good, or very
stupid. Or, you have to have a very limited number of images that you think
are so critically important that you’re willing to make a substantial
investment to make sure they survive a century.
Whichever, if it’s so important to save the image
that you’re willing to adopt John’s plan, only an idiot would
not add the insurance of doing things Andrew’s, Chris’s, and
Terry’s way also, just in case any one of them turns out right,
because all of them put together aren’t nearly as expensive as
John’s way.
Of these, the one that’s *least* likely to
survive is an LAB file. Color scientists, like color retouchers, always
like to fiddle with things. The chances of LAB being the scientific
colorspace of choice in a century is very small IMHO. Today, if somebody
gives you a file in CIELUV, what are you going to do with it? And yet
CIELUV was all the rage among color scientists, far less than a century
ago.
Dan Margulis
___________________________________________________________________________
Date: Tue, 16 Dec 2003 09:03:43 -0500
From: John Castronovo
Subject: Re: RGB Numbers
Are you assuming that when the transparency is the only
thing that survives it will be un-reproducible in any other format?
Certainly one will still be able to digitize the film 50 years from now,
and better that it can be done now. The reverse is still very much in
question. Ask any photo-conservationist or museum curator.
BTW, $110 is the going rate.
john castronovo
tech photo & imaging
___________________________________________________________________________
Date: Tue, 16 Dec 2003 08:37:13 EST
From: Paul Harding
Subject: Re: Re: RGB Numbers
In a message dated 12/16/03 3:22:50 AM,
wyseconsul@mac.com writes:
Terry “Give up being a comedian and keep your day
job” Wyse
Terry ..
PLEASE don’t give up! This site needs a lot of
levity .. understanding ..peace and good will .. “tis the
season”
Paul Harding
JIT Graphics
___________________________________________________________________________
Date: Tue, 16 Dec 2003 14:23:33 -0500
From: Lee Clawson
Subject: Re: RGB Numbers
John,
I’m trying to understand the actual number of
analogue to digital translations that have or will take place from the
original capture to the archive to the resultant exhibit print 50 or so
years from now.
I had thought that years from now either a print would
be made from the transparency (make an internegative then color photo) or
the transparency was the final form.
You explain the idea is to re-scan “digitize the
film 50 years from now”. I’m not as certain as you that film
and the tools to digitize it will be here in 50 years.
Lee
___________________________________________________________________________
Date: Tue, 16 Dec 2003 22:55:42 -0500
From: John Castronovo
Subject: Re: RGB Numbers
Certainly there will be ways to illuminate and
reproduce a film a hundred years from now. Film may not available, but it
shouldn’t be necessary. Nor will a scanner be needed, but copying
will be done somehow. We’ll probably just blink whatever we want to
reproduce onto a print using nanobots or live biological coloring enzymes
that mimic whatever they see. The important thing is that there will be a
real and viable image to reproduce.
john castronovo
________________________________________________________________________
Date: Tue, 16 Dec 2003 23:22:39 -0500
From: John Castronovo
Subject: Re: RGB Numbers
From: Dan Margulis
Seated in my beach chair, doing my best to stimulate
the Puerto Rican economy
by excessive consumption of Barrilito Three-Star, the
best rum in the world,
Now you’ve really proved your wisdom, and
we’re all appropriately jealous. Yours is certainly a better way to
spend the holiday season.
If the question is, what is the single form of storage
that is most likely to
be salvageable in a hundred years, I completely agree
with John Castronovo
that it’s an 8x10 transparency, however, his
argument with the others is moot.
This is an extremely expensive way of doing things. To
do it, you have to be
very wealthy, very good, or very stupid. Or, you have
to have a verylimited
number of images that you think are so critically
important that you’re willing
to make a substantial investment to make sure they
survive a century.
Probably so, but not every image needs a whole 8x10.
One can put 4 images on an 8x10 and quarter the cost. Now we’re down
to $25. Also, what is the cost to maintain a digital archive and be sure
that images are re-copied to new media every few years over 50-100 years?
(please, no one answer)
Anyway, I only offered it as a way to play
devil’s advocate. People are being told to ‘archive’
their film onto cd’s, and knowing what I know about technology and
hype, I thought it was reasonable to ask why they shouldn’t want to
‘archive’ their digital files onto something real - like film.
Take a rum in the sun, Dan.
john castronovo
___________________________________________________________________________
Date: Tue, 16 Dec 2003 23:11:23 -0800
From: Barry Rowland
Subject: Re: RGB Numbers
Assuming that folks will still be using some means of
snapping a picture, imagine the number of pixels available in a
point-and-shoot in 10 years, let alone...and it will be awfully easy to use
one of those to “digitize” that transparency into whatever the
file format flavour of the day is at that time...
Barry R.
___________________________________________________________________________
Date: Wed, 17 Dec 2003 08:18:54 -0500
From: Jonathan Clymer
Subject: Re: RGB Numbers
There are still a lot of glass negs from the 19th
century and film from the 20th century to be digitized. Interest in these
images will not go away, and the job of scanning them will not be complete
in 50 years or 100 years.
Jonathan Clymer
___________________________________________________________________________
Date: Wed, 17 Dec 2003 07:06:06 -0800
(PST)
From: Mike Bevans
Subject: Re: Re: RGB Numbers
This may interest folks:
http:
//diglib1.amnh.org/galleries/primates/primates.html
This is a collection of glass plate negatives, whcih
were scanned using a Jenoptik digital camera system. This is a flash site,
so they are lower res; however, I was a consultant on the job, and the
detail on the high res (100 megs) is amazing.
These are negatives that otherwise would never be
viewed by the public, and never would have been printed. Of course, the
coolest thing about this project is that it uses the latest in photographic
technology to revitalize an historically obsolete photographic technology.
Enjoy.
-Mike Bevans
www.tribecalabs.com
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