Dan Margulis Applied Color Theory
ProPhoto RGB or sRGB?
ProphotoRGB or sRGB
Posted by: "Wai-hong Chung"
Date: Fri Jun 30, 2006 8:58 am (PDT)
Hi All,
I normally shoot my photos in RAW and get them
printed in photo processing shop whose laser printer assumes sRGB
colorspace in the input files.
As you know, there are 4 choices of RGBs,
namely, Adobe RGB, ProPhoto RGB, Colomatch RGB and sRGB in the Camera Raw
space setting. I would like to use ProPhoto RGB and 16 bits because it has
the widest color gamut and are less prone to posterization after many curve
moves.
Please tell me whether it is advisable to
correct my photos in ProPhoto RGB and then change it to sRGB just before
taking it to photo processing shop for printing or should I use sRGB right
from the start from the Camera Raw space setting ?
Many thanks in advance !
Wai-hong Chung from Hong Kong
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Re: ProphotoRGB or sRGB
Posted by: "Maris V. Lidaka Sr.
Date: Fri Jun 30, 2006 1:06 pm (PDT)
Yes, it is advisable IMHO - and I would first save it
in ProPhoto RGB for possible future use before converting to sRGB for the
processing shop.
Maris V. Lidaka Sr.
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Re: ProphotoRGB or sRGB
Posted by: Andrew Rodney
Date: Fri Jun 30, 2006 1:09 pm (PDT)
That will work just fine, however, you may wish to
select an encoding color space based on scene gamut. In ACR, the Histogram
provides this useful feedback as you toggle to differing spaces. IF you see
a colored spike on either end of the Histogram in say Adobe RGB (1998),
this indicates there are colors out of gamut that you captured that can1t
be contained in this working space based on the current rendering you have
set. Toggle now to a larger space (ProPhoto RGB) and I'll bet the spikes go
away. However, say you don1t see the spikes in Adobe RGB (1998) or even a
smaller color space. Then use that working space since placing the bits
into a wider gamut space doesn1t buy you anything. In other words, if time
permits, encode into the smallest color space that fully contains the scene
gamut based on the clipping you see in ACR.
When you1re ready to go off to this lab, then or course
convert the master image into sRGB.
Andrew Rodney
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Re: ProphotoRGB or sRGB
Posted by: "Paul D. DeRocco"
Date: Mon Jul 3, 2006 4:55 am (PDT)
In my opinion, sRGB is a perfectly good color space,
unless your images have really saturated colors, especially yellows and
greens. Remember that your monitor probably doesn't cover very much of the
ProPhoto RGB color space (especially if it's an LCD), so editing in that
space means you're guessing about how saturated the greens really are. And
if you know that you're targeting an sRGB printer, I see no point in
editing in a wider space. As long as you keep the raw file, that is.
Ciao,
Paul D. DeRocco
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Re: ProphotoRGB or sRGB
Posted by: "Duffy Pratt"
Date: Mon Jul 3, 2006 5:02 am (PDT)
If your final space is sRGB, then I don't see what the
advantage is of working in a wider space for editing.
Whenever you move from PhotoPro to sRGB, you will lose
information that lies outside of sRGB's gamut. A narrower color space
is less likely to posterize than a wider one, as a matter of theory.
If you are editing either in 8 bits, there is a smaller distance
between the 256 levels in each channel, and thus less chance for strange
jumps between levels. Move to 16 bits, and the numbers change, but
the idea stays the same. In practice, I don't think it makes any
difference whether you edit in 8 or 16 bits.
I guess the question is whether there is any difference
in doing 2 conversions (RAW to PhotoPro to sRGB) or only 1 (RAW to sRGB).
I don't know the answer to this for sure, but my guess is that there
is probably no visible difference. It should be easy enough to test.
Duffy Pratt
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Re: ProphotoRGB or sRGB
Posted by: "Wai-hong Chung"
Date: Mon Jul 3, 2006 8:57 am (PDT)
Hello Duffy and Paul,
Thanks to your replies !
The argument is that doing
RAW>ProPhotoRGB>sRGB is that I can always have a wide gamut file for
future use and going from ProPhotoRGB to sRGB may conjure up better color
which I'm only guessing. The important point is, is there any harm from
doing ProPhotoRGB>sRGB ?
Wai-hong Chung from Hong Kong
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Re: ProphotoRGB or sRGB
Posted by: Andrew Rodney
Date: Mon Jul 3, 2006 9:09 am (PDT)
On 6/30/06 12:02 PM, "Duffy Pratt"
wrote:
If your final space is sRGB, then I don't see what the
advantage is of working
in a wider space for editing.
sRGB is never a final color space, always an
intermittent space (unless your only output is a display that behaves as
sRGB).
Whenever you move from PhotoPro to sRGB, you will lose
information that lies
outside of sRGB's gamut. A narrower color space
is less likely to posterize
than a wider one, as a matter of theory.
Not in 16-bit... If you have output devices that exceed
sRGB, you1ll lose a lot more data not working in a wider space.
IF your only output EVER is a display (and we would
have to excuse the new wide gamut displays that far exceed sRGB), then yes,
you never need anything other than sRGB.
Andrew Rodney
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Re: ProphotoRGB or sRGB
Posted by: "George Machen"
Date: Mon Jul 3, 2006 2:26 pm (PDT)
I'm not in front of Photoshop this weekend, but I
wonder if this use of the regular Photoshop histogram can be made when one
already is in an RGB or CMYK space, by converting to HSL (Hue Saturation
Lightness) and looking for spikes at the edges of the Saturation histogram
to indicate gamut clipping?
(I will second-guess Dan M. to say that one doesn't
need no stinkin' histogram when all that is necessary is to look at the
image for loss of detail in the saturated colors, but I'm just wondering if
what I'm saying in principle is correct.)
George Machen
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Re: ProphotoRGB or sRGB
Posted by: Andrew Rodney
Date: Mon Jul 3, 2006 8:53 pm (PDT)
On 7/3/06 10:28 AM, "George Machen"
wrote:
I'm not in front of Photoshop this weekend, but I
wonder if this
use of the regular Photoshop histogram can be made when
one
already is in an RGB or CMYK space, by converting to
HSL
(Hue Saturation Lightness) and looking for spikes at
the edges
of the Saturation histogram to indicate gamut clipping?
Photoshop1s histogram already provide a saturation
clipping in the histogram options set correctly. But, it1s too late
(you1ve encoded the data). ACR shows you this prior to rendering and
encoding.
Andrew Rodney
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Re: ProphotoRGB or sRGB
Posted by: "Rick Gordon"
Date: Mon Jul 3, 2006 9:00 pm (PDT)
I'm not personally convinced the the HSL filter is
capable of clarifying those judgements. The conversions look pretty rough
to me. I'm not sure I'd trust it in practice, even if the idea makes sense
in theory. However, I'd be interested in other's opinions regarding this.
Rick Gordon
___________________________________________________
RICK GORDON
EMERALD VALLEY GRAPHICS AND CONSULTING
___________________________________________________
WWW: http://www.shelterpub.com
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Re: ProphotoRGB or sRGB
Posted by: "Paul D. DeRocco"
Date: Mon Jul 3, 2006 9:00 pm (PDT)
I don't think you get any better color going
raw->ProPhotoRGB->sRGB, as opposed to raw->sRGB. You'll probably
get slightly different results, because profile conversions sometimes
involve some tweaking of the color. I don't think there's any harm in it,
though.
Ciao,
Paul D. DeRocco
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Re: ProphotoRGB or sRGB
Posted by: Marco Ugolini
Date: Mon Jul 3, 2006 9:31 pm (PDT)
Hi Paul.
In a message dated 6/30/06 8:05 PM, Paul D. DeRocco
wrote:
In my opinion, sRGB is a perfectly good color space,
unless your images have
really saturated colors, especially yellows and greens.
Plus reds, purples and cyans, which in sRGB all fall
short even of AdobeRGB.
Remember that your monitor probably doesn't cover very
much of the
ProPhoto RGB color space (especially if it's an LCD),
so editing in
that space means you're guessing about how saturated
the greens really are.
Although I have not explored this feature quite yet,
some monitor profiling packages apparently offer ways to compress
out-of-gamut colors, so that the user is able to perceive tonal
differentiations in area that are outside the gamut of one's display. I
have not tried these solutions yet, as I said, so I cannot say whether they
work well, but I intend to give them a try.
Also, the gamut of most "normal" displays
(ones that are not meant to cover AdobeRGB, for example) falls short even
of sRGB (mostly in the blue-purples, and occasionally in the cyan-greens),
so that even the use of sRGB is not fully free of problems and of
guesswork.
And if you know that you're targeting an sRGB printer,
I see no point
in editing in a wider space.
Two problems with that:
1) "sRGB printer" is an imprecise definition.
For example, the gamut shape of my Epson 2200 (using Premium Luster at
1440dpi) is short of sRGB almost all the way around, *except* in a very
meaningful range between green yellows and orange, where it pokes a
remarkable hole outside sRGB.
2) So the question there is: how do you preserve those
colors, specially if you start out by chopping them at the outset by
choosing sRGB? Even AdobeRGB does not fully contain that peak in my
printer's gamut, whereas ProPhoto RGB does. Of course, one has to decide
for himself how important it is to preserve those colors for one's own
specific type of work. If it isn't, then in that case sRGB may be alright.
As long as you keep the raw file, that is.
Isn't it impractical to go back to the RAW converter
every time one needs to repurpose an image?
Regards.
--------------
Marco Ugolini
Mill Valley, CA
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Re: ProphotoRGB or sRGB
Posted by: "Olivier"
Date: Tue Jul 4, 2006 3:43 am (PDT)
I'd agree with all, the issue would then be as far as I
am concerned not so much the working space choice (since either option
offers pros and cons) but rather the way to proceed depending on this
choice.
There's clearly clipping in any sRBG and
"small" gamut spaces, but somehow peripherals will often
encompass those spaces and larger, at the detriment of a full information
range.
Oppositely, in a prophoto space, at some stage the
display is to be needed to correct the image (it's hard to work only by the
numbers). The use of an output soft-proofing with out-of-gamut warning
helps a bit, but the file somehow becomes output dependent. Besides, even
though the display could be profiled with a perceptual rendering (which I
have experienced either), it's my belief the conversion will
"corrupt" the viewing in the sense the display and the video card
have their physical limitations.
I'm much tempted to benefit from the full power of ACR
and Prophoto, but I'm sure I miss a point to properly use it. Can expert
users share their knowledge here.
Olivier Desmaison
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Re: ProphotoRGB or sRGB
Posted by: "Paul D. DeRocco"
Date: Tue Jul 4, 2006 3:51 am (PDT)
From: Marco Ugolini
Plus reds, purples and cyans, which in sRGB all fall
short even
of AdobeRGB.
Cyans, yes, but I've never seen saturated cyans in real
life. As to reds and purples, sRGB and ARGB have the same red and blue
primaries, in the xy space. Only the green is much more saturated.
Although I have not explored this feature quite yet,
some monitor profiling
packages apparently offer ways to compress out-of-gamut
colors, so that the
user is able to perceive tonal differentiations in area
that are outside the
gamut of one's display. I have not tried these
solutions yet, as I said, so
I cannot say whether they work well, but I intend to
give them a try.
Standard gamma-based profiles assume relative
colorimetric rendering intent, so they just chop the out-of-gamut colors. A
full lookup table based profile (like a printer profile) lets you support
perceptual rendering intent. I don't know what software lets you do that
for monitors, though. Maybe ProfileMaker?
Also, the gamut of most "normal" displays
(ones that are not meant to cover
AdobeRGB, for example) falls short even of sRGB (mostly
in the blue-purples,
and occasionally in the cyan-greens), so that even the
use of sRGB is not
fully free of problems and of guesswork.
Yup.
1) "sRGB printer" is an imprecise definition.
For example, the gamut shape
of my Epson 2200 (using Premium Luster at 1440dpi) is
short of sRGB almost
all the way around, *except* in a very meaningful range
between green
yellows and orange, where it pokes a remarkable hole
outside sRGB.
Agreed. I have the 2200 too.
The original poster, if I remember correctly, was
talking about shipping his images out to some print shop that specified
that they wanted sRGB images. There are some printers out there that are
calibrated to behave like sRGB printers, although I expect that they, too,
don't really meet sRGB at all densities.
Isn't it impractical to go back to the RAW converter
every time
one needs to repurpose an image?
Depends. If you convert with CaptureOne, then it may
seem a chore to reconvert every time. If you use Adobe Camera Raw, then
you're just opening an image into Photoshop--no big deal.
Ciao,
Paul D. DeRocco
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Re: ProphotoRGB or sRGB
Posted by: Andrew Rodney
Date: Tue Jul 4, 2006 5:48 pm (PDT)
On 7/3/06 11:42 PM, "Paul D. DeRocco"
wrote:
The original poster, if I remember correctly, was
talking about shipping his
images out to some print shop that specified that they
wanted sRGB images.
There are some printers out there that are calibrated
to behave like sRGB
printers, although I expect that they, too, don't
really meet sRGB at all
densities.
Not really (they can1t). They assume sRGB for a source
color space for conversions to an output color space. A Fuji Frontier is an
example. I1ve profiled them and they don1t have a gamut that1s
significantly larger in many areas than sRGB but in no way behave or appear
like sRGB. The reference media is totally different too. The synthetic sRGB
color space was mathematically constructed to define a CRT display in a
very precise way (down to the ambient light this theoretical display
resides). I1ve never seen an emissive device that behaved like a reflective
print.
Andrew Rodney
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Re: ProphotoRGB or sRGB
Posted by: "Jim Goshorn"
Date: Tue Jul 4, 2006 5:48 pm (PDT)
On Jul 3, 2006, at 5:33 PM, Andrew Rodney wrote:
Photoshop’s histogram already provide a
saturation clipping in the histogram
options set correctly. But, it’s too late
(you’ve encoded the data). ACR
shows you this prior to rendering and encoding.
How do the options have to be set to show this?
Jim
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Re: ProphotoRGB or sRGB
Posted by: "Ric Cohn"
Date: Tue Jul 4, 2006 5:49 pm (PDT)
On Jul 4, 2006, at 1:42 AM, Paul D. DeRocco wrote:
Depends. If you convert with CaptureOne, then it may
seem a chore to
reconvert every time. If you use Adobe Camera Raw, then
you're just opening
an image into Photoshop--no big deal.
If your usual practice is to get the image exactly like
you want it in Camera Raw and then output, yes. However, most of this list
is about getting more out of an image. Unless there's a really really good
reason, I only want to do Channel blends, spotting, color adjustment, set
basic end points, go to Lab or CMYK, etc., etc. once. I'll then use this
file to repurpose.
Whether it's worth taking an image this far in
ProPhotoRGB (in which case you better stick with 16 bit as well) is a
matter of opinion, expectations, workflow, etc. Personally, I believe for
excellent image quality the kinds of adjustments listed above are far more
important than what color space one starts in. NOT that it doesn't ever
matter- just that it's worried about way too soon in the learning process
and given much more importance than I believe is warranted. It reminds me
of a beginning violin student who thinks if he could only use a
Stradivarius he would be able to play well.
My 2¢.
Ric Cohn
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Re: ProphotoRGB or sRGB
Posted by: "Walter Young"
Date: Tue Jul 4, 2006 5:53 pm (PDT)
Using the Place command to place the Raw file as a
layer allows you to double-click the layer to continually edit within ACR,
and even allows working in other color spaces by converting on the fly
after making the Raw edits.
The file must however be saved as a PSD to preserve the
Raw placed layer.
—Walter Young
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Re: ProphotoRGB or sRGB
Posted by: Andrew Rodney
Date: Tue Jul 4, 2006 6:09 pm (PDT)
On 7/4/06 1:57 AM, "Olivier" wrote:
Oppositely, in a prophoto space, at some stage the
display is to be
needed to correct the image (it's hard to work only by
the numbers).
Let1s see, the maximum red in both sRGB and ProPhoto
RGB are R255/G0/B0. So much for numbers.
Yes, the gamut limitation of displays is real. Even
with more wide gamut systems coming on line, those that now exceed Adobe
RGB (1998), you1re still in a situation where many colors cannot be viewed.
But cant these colors be output? Yes. The Epson K3 inks exceed in many
colors, Adobe RGB (1998). I just profiled the new Canon i5000 and it does
the same (although in different areas). Nice to have a 12 ink printer!
So you may be unable to see the colors on one device,
but you can reproduce them on another leading to the question, do you
squash down the file so you can see it all but lose a great deal of
potential colors you can output? Each user has to decide that for
themselves. Personally I1d like to stick with one rendered file from my
RAWs and be done with the RAW conversions. Since I have some images that
fall outside Adobe RGB (1998) and I can tell which based on the ACR
Histogram AND I want to be able to reproduce those colors on current
technology, the answer is ProPhoto RGB in 16-bit. Note that I often encoded
in smaller color spaces but only after viewing the capture/scene gamut
using the Histogram. I can assure you that a file captured on a Canon 5D
shooting of a gray card will fit in sRGB.
I'm much tempted to benefit from the full power of ACR
and Prophoto,
but I'm sure I miss a point to properly use it. Can
expert users
share their knowledge here.
There are no perfect RGB working space or we1d all use
just one. Scene gamut and the gamut of the captured image need to be
considered if you wish to contain and ultimately use those colors on
output. In the last few months, a 12 ink, very wide gamut and affordable
ink jet printer was released. I have no idea what kind of output technology
we1ll see in a year, let alone 5 years and yes, I occasionally capture
images I1d love to print in the future. So for me, it1s pretty simple;
capture and hold all the colors possible. I know I can1t see them on one
device (the display) or reproduce them on others (press) but I1d rather
have them for output to devices where the colors can be used.
Andrew Rodney
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Re: ProphotoRGB or sRGB
Posted by: "George Machen"
Date: Wed Jul 5, 2006 12:01 pm (PDT)
Andrew Rodney wrote:
Photoshop1s histogram already provide a saturation
clipping in the histogram
options set correctly.
I don't see a Saturation choice among the Histogram
palette's Colors popup menu. There is a Luminosity and a Colors, the latter
of which is the only one I can find that you might be meaning. Unless I'm
missing something. But isn't the Colors an amalgam of Hue & Saturation?
It purely wouldn't show gamut clipping, would it? That's why I was thinking
of making these inspections in HSL.
But, it1s too late (you1ve encoded the data). ACR
shows you this prior to rendering and encoding.
Oh yeah, I know. But I'm not coming out of ACR; I'm
talking about looking at what happens going into a lower-gamut space from a
wider-gamut one in an existing image, and how steps I have taken to
mitigate gamut clipping (e.g., channel blending) have worked out. And I do
have an undo.
George Machen
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Re: ProphotoRGB or sRGB
Posted by: Andrew Rodney
Date: Wed Jul 5, 2006 3:37 pm (PDT)
Setup the info palette to show all colors so you get
individual red, green and blue histograms. Within each, if you see a spike
on either end that represents zero or 255, the indicates saturation
clipping. Only when all three produce zero or 255 are you showing the
clipping of tone (shadow or highlight). So, if Red and Green are 255 but
blue is say 253, you1re seeing that red and green are clipped.
Another way to see this is to use the clipping overlay
in Levels. Hold down the Alt/Option key and slide the black or white input
sliders. So if you do this on the white input slider, when you see a white
pixel, that indicates all three channels are clipping. However, a single
color shows you which color is clipping (red green or blue indicates a clip
of that color. Cyan would indicate green and blue channel clipping, Yellow
Red+Green, Magenta, Red+Blue).
However, its vastly more useful to do this in the RAW
converter and see the effect of larger and smaller gamut encoding spaces
based on the current rendering. Once the file is rendered, you really have
no idea what was past the individual color channels with respect to
saturation clipping. True for tone as well although the only way to recover
clipping of all three channels is to start plying with the actual rendering
controls.
Andrew Rodney
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Re: ProphotoRGB or sRGB: Is plotting helpful?
Posted by: "Sonny"
Date: Wed Jul 5, 2006 3:46 pm (PDT)
I am somewhat of a novice, and wonder if this procedure
is helpful. I don't process many images, and time is not an issue. And, I
hope to learn some fundamentals.
In ACR I check the Histogram to see if ProPhotoRGB
decreases clipping, and if so, use that rather than aRGB.
Since my monitor (Eizo CE240W) does not show more than
sRGB, I can't even vizualize the additional gamut that ProphotoRGB would
offer.
So, I am playing with ColorThink. I plot 1) the image
colors (drag the image onto the plot), 2) the working space(s), and 3) the
printer (R2400) profile. Then I look at the plot to see if my printer can
print those additional colors offered by ProphotoRGB.
It takes only a few minutes, but I am wondering if this
really gives accurate info, or, is it just theoretical?
Thanks very much,
Sonny Taylor
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ProphotoRGB or sRGB: Is plotting helpful?
Posted by: Andrew Rodney
Date: Wed Jul 5, 2006 11:07 pm (PDT)
On 7/5/06 1:02 PM, "Sonny" wrote:
So, I am playing with ColorThink. I plot 1) the image
colors (drag the
image onto the plot), 2) the working space(s), and 3)
the printer (R2400)
profile. Then I look at the plot to see if my printer
can print those
additional colors offered by ProphotoRGB.
It takes only a few minutes, but I am wondering if this
really gives
accurate info, or, is it just theoretical?
This is an excellent tool to view all this. What1s
great is you could render the same RAW file in one or more working spaces
and load that image in ColorThink along with your printer profile. The
image appears as 3dots2 of actual color and you can spin that in 3D to see
how it maps in relationship to the output device gamut. Having the ability
to spin this in 3D really aids in seeing what will or will not clip from
the image.
I1d be less worried about messing with the display
profile. As I said, with today1s display technology, the gamut is a
limitation however, the gamut of the scene and capture device (which really
has no gamut) and the output device at least allows you to get an idea of
what you can capture and actually output to the printer. Both devices far,
far exceed the gamut of the display.
Try shooting some very saturated scenes in RAW using
the above tools in ColorThink, then try a very muted scene as well. A very
educational tool and process!
Andrew Rodney
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ProPhoto (Wide gamut) spaces for RAW processing
Posted by: Andrew Rodney
Date: Fri Jul 7, 2006 3:30 pm (PDT)
VERY interesting Podcast discussing how Adobe Lightroom
(and Adobe Camera RAW) are designed via a wide gamut, linear encoded
ProPhoto RGB space with Bruce Fraser, Thomas Knoll (the father of Photoshop
and ACR) and Mark Hamburg can be found here:
http:
//photoshopnews.com/2006/07/07/lightroom-podcast-episode-8-posted/
Very worthwhile color theory discussions.
Andrew Rodney
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Re: ProPhoto (Wide gamut) spaces for RAW processing
Posted by: "Ric Cohn"
Date: Sat Jul 8, 2006 4:45 pm (PDT)
On Jul 7, 2006, at 3:29 PM, Andrew Rodney wrote:
VERY interesting Podcast discussing how Adobe Lightroom
(and Adobe Camera
RAW) are designed via a wide gamut, linear encoded
ProPhoto RGB space with
Bruce Fraser, Thomas Knoll (the father of Photoshop and
ACR) and Mark
Hamburg can be found here:
Yes, very interesting. The blending of ProPhoto gamut
with sRGB encoding was way over my head. Sounds interesting, although I
couldn't grasp if this creates a better behaved wide gamut space or what
other advantages there might be. Andrew, care to share any more info on
this?
It does seem that virtually all the heavy hitters on
the Photoshop team are advocating ProPhotoRGB as a standard working space.
If nothing else it seems to guarantee, for better or worse, that many more
people will be using ProPhotoRGB in the future. I guess that we will see if
there are any problems that arise more, or less, frequently because of
this. If nothing else it would finally "prove" the advantages of
16 bit editing, as I believe editing ProPhoto in 8 bits is virtually a
guarantee of inferior results.
Ric Cohn
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Re: ProPhoto (Wide gamut) spaces for RAW processing
Posted by: Andrew Rodney thedigitaldog
Date: Sat Jul 8, 2006 8:12 pm (PDT)
On 7/8/06 4:46 PM, "Ric Cohn" wrote:
Yes, very interesting. The blending of ProPhoto gamut
with sRGB
encoding was way over my head.
In a nutshell, the native space is ProPhoto RGB (at
least it's primaries) but instead of the usual gamut tone curve (better to
say tone response curve) its linear. RAW data is linear, makes sense.
However, if you viewed such a Histogram, it look pretty odd, all pushed to
one side. So the Histogram is represented as a gamma corrected color space.
The display preview is funneled into sRGB.
Sounds interesting, although I
couldn't grasp if this creates a better behaved wide
gamut space or
what other advantages there might be.
It is what it is, linear but represented with a gamma
correction (otherwise, folks would look at the Histogram and say 3oh my
god2).
It does seem that virtually all the heavy hitters on
the Photoshop
team are advocating ProPhotoRGB as a standard working
space.
For RAW processing yes. But you can encode that into
four color spaces, all gamma corrected: sRGB, ColorMatch RGB, Adobe RGB
(1998) or ProPhoto RGB.
If nothing else it seems to guarantee, for better or
worse, that many
more people will be using ProPhotoRGB in the future.
As the internal RAW to RGB color space yes but that1s
not presented to the user. They can ask for a gamma corrected ProPhoto
space or any of the other three spaces (based if done correctly on the
Histogram that shows clipping, should scene gamut exceed those three
encoding color spaces).
RAW is Grayscale data. It1s linear encoded. These
sensors on these digital cameras are simply photon counters and record the
light striking them in a linear fashion. Each level recorded produces the
same, corresponding level of data in the RAW file. If one photon strikes
the sensor representing the first dark tone that can be recorded, the
result is level 1 in a digital file. If 4096 photons strike the sensor,
representing the brightest value it can record, then the result is level
4096 in a digital file. When you encode into a gamma correct working space
(usually 2.2 or 1.8), the tones and histogram are remapped and look as most
users expect. That's the point Thomas (or Mark) made about having to use a
gamma correct histogram even though the processing is all linear.
Andrew Rodney
Encode appropriately and convert as needed just before
print time. You have the most flexibility with the data.
As far as I know, this is not a concern of the original
poster, the
lab with sRGB input to their printer is the only
concern.
If it's not a concern now, it might be in the future.
If he starts with the most data and funnels it down for the lab, the lab
will do fine and he'll have data he might be able to use later. The
alternative offers none of this flexibility or safety.
Andrew Rodney
___________________________________________________________________________
...and around a month later:
Color Management Workflow for RAW files Editing
Posted by: "Wai-hong Chung"
Date: Tue Aug 1, 2006 12:41 pm (PDT)
Hi All,
Recalling my earlier enquiry on whether using
ProPhoto RGB or sRGB as working space, after consolidating the replies, I
come up with the following color management workflow. I would like you to
provide your comments.
First of all, I'm a amateur. I use a Minolta A200 to
shoot RAW files. I use a CRT monitor which has a color gamut similar to
sRGB and I take the files to a commercial lab to print the photos who use a
Fujifilm Frontier minilab which assume its input files as sRGB.
As advised by Andrew Rodney, I used ACR histogram to
check whether there is any color spike to see whether there is any out of
gamut color. If there isn't any, then I used sRGB all the way to print.
However, if there are color spikes, I use ProPhoto RGB to remove them.
Then, I use ProPhoto RGB as working space for editing. I know I'm guessing
the out of gamut color on my CRT display, but I want to keep a wide gamut
file to cater for future advance in technology. In the midlle of the
editing, I might also convert the file to LAB for color correction but that
dosn't matter. After editing, I save a copy of the ProPhoto RGB file and
then convert the file to sRGB choosing perceptual rendering intent for
heavily saturated color photos. However, I would always toggle between
perceptual intent and relative colorimetric intent to suit my taste in the
convert to profile dialog box. After converting to sRGB, I make minor color
adjustments. I also used 16 bits for both the ProPhoto RGB
& sRGB to cater for the many curve editing to
avoid posterization. Then I take the sRGB files to the lab for
printing.
I would be most grateful if you would tell me your
color management workflow for RAW files editing as well.
TIA!
Wai Hong Chung from Hong Kong
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Ric Cohn"
Date: Tue Aug 1, 2006 4:07 pm (PDT)
As long as you're using more than one color space I'd
suggest using AdobeRGB when the colors fit there but not sRGB. Also, you
don't say if you're working in 8 bit or 16 bit. IMHO when using ProPhotoRGB
you should use 16 bit-- the info is spread so thin that unlike the more
traditional spaces, I believe, large corrections in ProRGB have been
shown to cause "see-able" damage when performed on 8 bit data.
Ric Cohn
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Stephen Marsh
Date: Tue Aug 1, 2006 5:41 pm (PDT)
Wai-hong Chung wrote:
As advised by Andrew Rodney, I used ACR histogram to
check whether
there is any color spike to see whether there is any
out of gamut
color. If there isn't any, then I used sRGB all the way
to print.
However, if there are color spikes, I use ProPhoto RGB
to remove them.
Dear Wai-hong, please refer to my post here in regards
to converting between a larger matrix based working space and a smaller one:
http://groups.yahoo.com/group/colortheory/message/14486
"Many get so caught up on the first point, that
they toss it all out when performing the second. Perhaps this is becuase
all one hears about is the theory, rather than putting it to good
use."
After editing, I save a copy of the ProPhoto RGB file
and then
convert the file to sRGB choosing perceptual rendering
intent for
heavily saturated color photos. However, I would always
toggle between
perceptual intent and relative colorimetric intent to
suit my taste in
the convert to profile dialog box.
This does not work going to sRGB, no perceptual, you
only have RelCol and clipping, thus you are loosing all the extra work you
have done in ProPhoto.
Regards,
Stephen Marsh.
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Marco Ugolini
Date: Wed Aug 2, 2006 3:53 am (PDT)
Unfortunately, when you have matrix-based profiles as
both your source and target, as is the case here, changing the rendering
intent does not change the results. That's just the way it works.
Regards.
--------------
Marco Ugolini
Mill Valley, CA
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Dan Margulis"j
Date: Wed Aug 2, 2006 8:25 am (PDT)
Ric writes,
Also, you don't say
if you're working in 8 bit or 16 bit. IMHO when using
ProPhotoRGB you
should use 16 bit-- the info is spread so thin that
unlike the more
traditional spaces, I believe, large corrections in
ProRGB have been
shown to cause "see-able" damage when
performed on 8 bit data.
This is not correct. It has been shown that making
major corrections in an ultra-wide gamut RGB can produce results that are
visibly *different* when 16-bit is used rather than 8-bit. This is as
opposed to more rational RGBs, where any series of real-world moves produce
results that are indistinguishable for quality.
Making big moves in an ultra-wide RGB would yield
similar results to doing it in a grayscale file. Most of the time there's
no visible difference; occasionally an area (or a whole image) will look
better if done in 16-bit--and around three times as often, it will look
better if done in 8-bit.
The differences show up in areas where the 8-bit file
is already suspect and the extra eight bits contain nothing but random
numbers. Skies, strongly colored areas, and deep colors are examples. In
these cases, using 16-bit amounts to applying a sophisticated form of
blurring. In skies and shadows that may help, everywhere else, it hurts.
The bottom line is, that if anyone choosing to make
major edits in an ultra-wide RGB--a practice that has no advantages at all,
AFAIK, and a lot of disadvantages--needs to be aware not just of the times
that 16-bit is better, but of those when 8-bit is better, as opposed to the
rest of us, who can use either one whenever we like.
Watching this thread develop while on vacation a few
weeks back was a depressing experience. Once again, we saw people who don't
understand what histograms show advising others to take action based on
what histograms do not show.
Paul DeRocco made one of the only sensible posts,
pointing out that even sRGB is suitable for most applications, because the
colors in which it is theoretically weak don't exist in nature. I can't
locate a single real image in which sRGB is inadequate for CMYK output. I
*surmise* the existence of real images for which sRGB is inadequate for
better conditions. I *don't* surmise that any real color photographs or any
output conditions would be unsuitable for something moderate-gamut like
ColorMatch RGB, let alone something as huge as Adobe RGB.
Before we talk about anything bigger than Adobe RGB,
let's first see an example of a real-world photograph that somebody thinks
is printable under any current output conditions, yet unsuitable for
ColorMatch RGB--or even sRGB.
Dan Margulis
___________________________________________________________________________
Re: Color Management Workflow for RAW files
Editing
Posted by: "Terry Wyse"
Date: Wed Aug 2, 2006 10:56 am (PDT)
Forgetting about wide vs. "rational" RGB
working spaces for the moment, are you saying that working in 16-bit can
actually HARM images? Do you have any examples where this has occurred? I
can accept the argument that 16-bit may be of questionable value for a
majority of images but to imply that 16-bit is harmful - well, I just can't
buy that assuming there are no bugs in the way Photoshop handles
16-bit/channel editing.
In regards to "real world" images, are you
discounting the fact that someone may PREFER a more highly-saturated
rendering of a "real-world" photographic scene as opposed to one
that is "accurate" or faithful to the original scene? I would
contend that virtually no one would prefer an "accurate"
rendering of a scene and would prefer instead a bit of added
"punch" as being more pleasing. Acknowledging that this may be
the case for a majority of photographs, it then only becomes a matter of
degree to which this preference may be contained in a smaller space such as
sRGB or that it may "punch-out" or sRGB and require a larger
container/color space.
To further bludgeon this near-dead horse, one can also
demonstrate that, in fact, current inkjet technology (and I assume
photographic imaging technology) can not only exceed sRGB but can indeed
exceed parts of the "huge" AdobeRGB space. In my mind, if a
current printing technology can be demonstrated to exceed several of these
so-called rational color spaces, these now become REAL colors that I can
print requiring a color space that will contain them and are not simply
some theoretical colors that I MAY be able to print and should allow for in
the hopes some future imaging technology comes along that will permit this.
No, these are colors that I CAN print today and might well WANT to print
depending on how I chose to render a real-world image.
Regards,
Terry Wyse
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Wai-hong Chung"
Date: Wed Aug 2, 2006 10:57 am (PDT)
Dear Marco Ugolini and Stephen Marsh,
Thanks to your reply. Do you mean that changing from
ProPhoto RGB to sRGB using perceptual rendering intent is just like
relative colorimetric intent which is the out-of-gamut colors will got
clipped! In fact, I've tested by toggling the 2 rendering intent and I
found there is no difference between them for out-of-gamut color. Under
what situation will there be a visible difference when toggling between the
perceptual and relative colorimetric intent ? TIA.
Wai Hong Chung from Hong Kong
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Matthew Rigdon"
Date: Wed Aug 2, 2006 1:22 pm (PDT)
There's been some other discussions about bit-depths
and what-not and I believe it was mentioned that internally most of the
D-SLRs of 35mm and APS-C sensor size are 12-bit processors. Throw the
number conversion of a color-profile into the mix, and you're going to come
up with some variation in color numbers depending on what algorithm you
use, how you handle rounding errors, etc. Depending on the image, the
program doing the work, the gamma curve of the profile, etc, you're bound
to find some cases where a 16-bit conversion could damage an image. I guess
it comes down to a question (and an image processing programmer would
better answer this) of whether you run into more problems padding values in
an image or dropping values in an image.
And never underestimate the abilities for bugs to crop
in a software tool, especially one as complicated as Photoshop. I've heard
a number of complaints in online forums about the way in which Camera Raw
handles conversions compared to other RAW conversion tools. This is
obviously going to compounded by the fact that most of the Camera
manufacturers keep their RAW formats undocumented to outsiders, so a lot of
the work the Photoshop team does is trial-and-error, especially when a
camera first comes out.
I only talk about cameras as this is probably the most
popular way of grabbing digital images right now and what I have experience
with. If you're working with a scanner pulling images off film, you may
never see a problem.
Just my two cents,
Matthew Rigdon
___________________________________________________________________________
Re: Color Management Workflow for RAW files
Editing
Posted by: "Ric Cohn"
Date: Wed Aug 2, 2006 4:36 pm (PDT)
On Aug 2, 2006, at 10:08 AM, Dan Margulis wrote:
This is not correct. It has been shown that making
major corrections in an
ultra-wide gamut RGB can produce results that are
visibly *different* when
16-bit is used rather than 8-bit. This is as opposed to
more rational RGBs, where any series of real-world moves produce results
that are indistinguishable for quality.
I did mark this as my opinion, and I'm not ready to
change it. However, I do want to make clear that I was not advocating using
ProPhotoRGB, just pointing out what I think needs to be done to protect
your images if you believe ProPhotoRGB makes a difference. I don't use it
because I don't see any benefits for my images and I would rather take
pictures than do endless tests looking for the one image that might
theoretically be improved slightly if I took on a more difficult and error
prone workflow. However, I'm not knowledgeable enough to tell experts (who
may be wrong about this area, but still know more than I do in their areas
of expertise) that they are wrong. I'll leave that to other experts
<g>.
I will also wait for the advocates to show me the
images that prove their points. Maybe if they show me images where it makes
a difference I will be able to see their point (and even learn something
which is more than I can say now).
Ric Cohn
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Stephen Marsh
Date: Wed Aug 2, 2006 4:37 pm (PDT)
Thanks to your reply. Do you mean that changing from
ProPhoto RGB to
sRGB using perceptual rendering intent is just like
relative colorimetric intent
which is the out-of-gamut colors will got clipped!
Yes.
In fact, I've tested by toggling the 2
rendering intent and I found there is no difference
between them for
out-of-gamut color.
Then why does the software interface allow one to
select an option that has no effect, with no warning that the user selected
option that is invalid or going to be ignored and another option used
instead? Why is the option not greyed out? Why do users need to learn so
much "useless" information about profiles just to drive a
colour conversion correctly?
Don't bother answering, these are rhetorical questions.
Perhaps we will have a future version of Photoshop that
is smarter in how it presents the 'loose' nature of ICC profiles, or
perhaps smarter ICC profiles if this is beyond the ability of Photoshop.
Under what situation will there be a visible
difference when
toggling between the perceptual and relative
colorimetric intent ? <<
When converting to a table based profile, instead of a
matrix based one. An easy way to look at the file size of the profile.
As a general rule*, table based profiles are
usually/commonly found in output profiles, such as RGB or CMYK printer
profiles. In the Adobe v2 CMYK profiles, which are built with special Adobe
ICC generation software - the perceptual transform is rather tame, more
like RelCol in that the transform is closer to the original on the monitor
after conversion. Profiles built by publicly available third party software
have more variation in their perceptual transform (what some call special
sauce or secret sauce, the proprietary method used for compression specific
to the software), after conversion the image is often very different to the
RGB or a RelCol transform - but on press or inkjet this may be more
appealing, depending on personal taste and other factors. It appears that
the ICC does not specify how gamut compression is achieved, only that it
can be offered as one of the four intents when converting (a profile may
not have all four intents, even though CMM software allows one to select
them).
It does seem a major flaw that working space profiles
do not offer this proprietary method.
*An exception to the general rule:
http://www.josephholmes.com/profiles.html
Joseph Holmes has a family of table based profiles for
sale (there is a matrix based free profile for download and a PDF with more
info on the table based family profiles that are same/similar in gamut to
the free matrix profile), I have not used them and can't vouch for their
usefulness - but at least there is one person offering RGB film type gamut
working space profiles that offer gamut compression.
But I would ask again - does the image contain these
wide gamut colours in useful areas and is the output actually better off
even if it can make use of the wider gamut.
Regards,
Stephen Marsh.
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Wai-hong Chung"
Date: Fri Aug 4, 2006 3:10 am (PDT)
Hi All,
Thank you all for giving me so many valuable
advices regarding the captioned subject, in particular to Mr. Andrew Rodney
who advised me of the PhotoGamut RGB. I have test this profile and at last
I've found a RGB space which has response to perceptual rendering intent
(i.e. when I toggle between RelCol and perceptual, there is a visible
difference). When I print a real world photo using the PhotoGamut RGB
space, I found it give brighter color than sRGB.
May I take this opportunity to request those of
you who know the Adobe Photoshop programmers to tell them to include
perceptual rendering intent when converting to sRGB in the next update of
Photoshop.
The more I learn, the more I found I don't know
!
Wai Hong Chung from Hong Kong
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "colorman042000"
Date: Fri Aug 4, 2006 7:33 am (PDT)
convert the file to sRGB ... (cut)
Dear Wai Hong Chung,
Editing in ACR using ProPhoto as your color space when
your final output is sRGB can result in inferior images as I have found
many times. For instance, if you edit bright saturated reds in "ACR-
ProPhoto" you will most probably end up with reds
that are way outside the sRGB gamut so when you eventually convert to sRGB
those reds will be clipped. Since color = detail then clipped colors =
clipped details.
My experience with real-life photos have shown that if
the final output is sRGB then you should definitely do your ACR corrections
using the sRGB color space.
Andre Dumas
___________________________________________________________________________
Re: Color Management Workflow for RAW files
Editing
Posted by: Dan Margulis
Date: Fri Aug 4, 2006 7:33 am (PDT)
Terry writes,
Forgetting about wide vs. "rational" RGB
working spaces for the
moment, are you saying that working in 16-bit can
actually HARM
images?
I don't understand this word "harm". I am
interested only in which method produces a better image. They are two
different calculations. With a rational RGB it won't matter which one you
use. Under conditions of severe stress, such as making major corrections in
an ultra-wide RGB, it *can* make a difference. When it does, the viewer may
prefer one way or the other. It is more common to prefer the 8-bit under
these circumstances.
Do you have any examples where this has occurred?
If you are asking whether there are any real-world,
rational RGB images where correcting in 8-bit got a better result than
doing the same thing in 16-bit, no, no more than a 16-bit correction ever
does better than 8-bit in the real world. When you get into the exotic RGB
and other non-real world image category, yes, you've seen them.
Notably, in one of the examples shown on another list and discussed
here, the 16-bit advocate's idea of a real-world image was to acquire a
normally lit capture in Camera Raw with the Exposure setting as far to the
left as possible, making it grossly dark. This procedure was correctly
described by another list member as a "never in a million years"
kind of thing.
He then applied the drastic corrections needed to
reverse his own sabotage, on both an 8- and 16-bit file, and called
attention to the deepest shadows, where the 16-bit version was indeed
softer. However, looking at the image as a whole, everyone who examined it
concluded that the 8-bit version was superior. This effect is similar to my
own findings in B/W. Anyone making major corrections in an ultra-wide RGB
needs to be aware of it--there are more cases where 8-bit is superior than
the other way round. (Again, in a rational RGB it doesn't matter which you
use).
In regards to "real world" images, are you
discounting the fact that
someone may PREFER a more highly-saturated rendering of
a "real-
world" photographic scene as opposed to one that
is "accurate" or
faithful to the original scene?
No.
I would contend that virtually no one
would prefer an "accurate" rendering of a
scene and would prefer
instead a bit of added "punch" as being more
pleasing. Acknowledging
that this may be the case for a majority of
photographs, it then only
becomes a matter of degree to which this preference may
be contained
in a smaller space such as sRGB or that it may
"punch-out" or sRGB
and require a larger container/color space.
Do you have an example image to show us?
In my mind, if a current printing
technology can be demonstrated to exceed several of
these so-called
rational color spaces, these now become REAL colors
that I can print
requiring a color space that will contain them and are
not simply
some theoretical colors that I MAY be able to print and
should allow
for in the hopes some future imaging technology comes
along that will
permit this.
This does not speak to the point made both by me and
Paul DeRocco. Even accepting the vendors' claims that they can hit such
colors, which I do not accept, or that human beings can perceive minor
differences in them, which I do not accept either, the question becomes
whether you have any files that would actually take advantage of these
purported capabilities.
No output device approaches any of these RGBs except in
dark, saturated yellows, magentas, and cyans. The better the output
conditions, the bigger the range of these potentially problematic colors,
but no device creates a problem for these RGBs in red, green, and blue.
Variations in extremely saturated yellows are inconsequential as nobody can
see them. The problems with magentas and cyan are potentially real--as long
as you can find an image that wants to use these colors. I suggest that you
probably can't.
No, these are colors that I CAN print today and might
well WANT to print
depending on how I chose to render a real-world
image.
Then it shouldn't be too much trouble for you to show
us the kind of image you have in mind--a real-world color photograph with
discernable detail that only LAB or an ultra-wide RGB can retain, and yet
is printable on any existing device.
Dan Margulis
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Andrew Rodney thedigitaldog
Date: Fri Aug 4, 2006 9:06 am (PDT)
On 8/4/06 7:51 AM, "colorman042000"
wrote:
Editing in ACR using ProPhoto as your color space when
your final
output is sRGB can result in inferior images as I have
found many
times.
Can you post some RAWs and rendered examples?
For instance, if you edit bright saturated reds in
"ACR-
ProPhoto" you will most probably end up with reds
that are way outside
the sRGB gamut so when you eventually convert to sRGB
those reds will
be clipped. Since color = detail then clipped
colors = clipped details.
Of course itxs clipped, you went from a much larger
color space (one you hopefully selected to contain colors captured
otherwise why select it?) to a smaller one (because that sRGB color space
is appropriate for some use). Now if you have the ProPhoto image and need
to output to say a $600 Epson 2400, you can use those colors since itxs far
more capable of producing the extended gamut that sRGB canxt.
Andrew Rodney
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Andre Dumas
Date: Fri Aug 4, 2006 10:03 am (PDT)
Terry Wyse wrote:
one can also demonstrate that, in fact, current inkjet
technology (and I assume photographic imaging
technology) can not
only exceed sRGB but can indeed exceed parts of the
"huge" AdobeRGB
space. ..
Isn't it a fact that inkjets are dependent to a large
extent on the profiles that one has built for his own particular printer?
If one's profiles are somewhat deficient in the reds for instance, isn't it
possible then that the inkjet might not reproduce those reds correctly even
if they are well within its gamut?
If so then, when we talk about the large gamut of the
Epson 2200 and other printers should we not talk about, and take into
consideration, the gamut of the profiles that we are using, and should we
not recognize that few people have access to really good profiles for their
very own printer and for all their papers and printing conditions?
Andre Dumas
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "MARK SEGAL"
Date: Fri Aug 4, 2006 11:05 am (PDT)
Andre,
The Epson 2400 and X800 series using the Epson
K3 inkset do have wider gamut in some respects than that of its immediate
pre-decessors, the Epson 2200 and the 4000/7600/9600 series. This shows on
gamut plots and printer test charts that I have seen presented. The gamut
plots also show that these printers' gamuts exceed that of ARGB98 in in
some respects.
Based on extensive experience using both the
Epson 4000 and the Epson 4800, and having various custom profiles made for
both machines, and comparing my results with those obtained on other
similar machines using a well-known and respected RIP, I find that the
profiles which Epson supplies for its own papers are indeed VERY good on
their professional machines (4000/4800 upward). Owners of these machines
would have to go to some lengths to improve upon them.
The remaining issue, which Dan has raised I
believe, is whether "real world images" would actually contain
those colours at the edge of the printer's gamut such that one would want
to print them (and therefore wish to have the larger working space from
which to draw upon them). The answer to that question in my case is YES,
especially for reds. People who have done alot of photography in Thailand
and China will know what I mean.
Mark Segal
___________________________________________________________________________
Color Management Workflow for RAW files Editing
Posted by: "Richard Chang"
Date: Fri Aug 4, 2006 11:09 am (PDT)
Terry writes,
I would contend that virtually no one
would prefer an "accurate" rendering of a
scene and would prefer
instead a bit of added "punch" as being more
pleasing. ...
I would contend that virtually no one in the off-figure
catalog business would prefer anything less than accurate. Because
customers commonly lay a garment across the catalog page to see if that
rendered image goes with an outfit they already have, the image must be
accurate. Returns of product, based on non-accurate rendering of
color specific goods, can impair a clothing retailer's bottom line in a
hurry.
Richard Chang
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Terry Wyse"
Date: Fri Aug 4, 2006 3:32 pm (PDT)
Assuming a good (professional) profiling application
has built the profile, if the profile happens to be deficient in red, by
definition so is the printer. The printer defines the gamut of the profile,
not the other way around.
I'm, naturally, assuming the use of custom profiles not
mystery-meat profiles downloaded from questionable sources.
Regards,
Terry Wyse
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Andrew Rodney thedigitaldog
Date: Fri Aug 4, 2006 3:32 pm (PDT)
The profile defines and describes the color space
(gamut) of the device.Therexs no adding or artificial gamut although there
are differing ways ofmapping out of gamut colors to the gamut of the
device.
The gamut of many ink jet printers requires a color
gamut significantlylarger than sRGB (and in some cases Adobe RGB (1998)) if
you wish toreproduce all captured colors also outside that gamut.
Andrew Rodney
http://www.digitaldog.net/
___________________________________________________________________________
Re: Color Management Workflow for RAW files
Editing
Posted by: Andre Dumas
Date: Fri Aug 4, 2006 3:32 pm (PDT)
I have posted "petunias" in the Photos
section. This was opened directly from the RAW, it was adjusted in
RAW but unmodified after opening except that it was cropped and saved to a
JPEG.
Andre Dumas
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: "Matthew Rigdon"
Date: Fri Aug 4, 2006 7:12 pm (PDT)
I opened your file and assigned an sRGB file (i assume
you used sRGB, you didn't specify how you did the conversion to JPEG, but
most converters use sRGB since JPEG is assumed to be for web work).
I put up a picture of some ducklings that I took in an
album called "Ducklings at a Red Trough". The little feed trough
is a rather intense red color, maybe not exactly the same red as your
petunias, but something with a good amount of saturation. It seems sRGB can
handle intense red shades (your image looks very flat and desaturated).
If the issue is that you just let the machine convert
to sRGB and it came up with that, that doesn't necessarily represent a
failing on the part of sRGB. It may have just needed a different adjustment
before the conversion. Of course, you'd need to know you were going to sRGB
to begin with. I don't think any of the profiles or conversion methods can
always be expected to be done without operator assistance.
Matthew Rigdon
___________________________________________________________________________
Re: Color Management Workflow for RAW files
Editing
Posted by: Ric Cohn
Date: Fri Aug 4, 2006 7:13 pm (PDT)
Andre,
Not sure what you uploaded. I've noticed before that
Yahoo strips any profile and resamples the jpeg when it uploads. Was this
edited and output as ProPhotoRGB? If I assign ProPhotoRGB to it the red
becomes super bright and, at least on my Laptop, large areas of the reds
are outside the monitors gamut and appear flat red even though the channels
aren't clipped.
Please elaborate on your point- it appears to be an
interesting one.
Ric Cohn
___________________________________________________________________________
Re: Color Management Workflow for RAW files Editing
Posted by: Marco Ugolini marcougolini2
Date: Fri Aug 4, 2006 10:53 pm (PDT)
In a message dated 8/4/06 9:33 AM, colorman042000 wrote:
Isn't it a fact that inkjets are dependent to a large
extent on the
profiles that one has built for his own particular
printer? If one's
profiles are somewhat deficient in the reds for
instance, isn't it
possible then that the inkjet might not reproduce those
reds
correctly even if they