Dan Margulis Applied Color Theory
Photoshop LAB Color Arrives
Date: Mon, 25 Jul 2005 21:42:55 -0500
From: "drhobbes"
Subject: Professional Photoshop
Dan,
Apparently your LAB book will be in the bookstores in
the first week or two of August. Now that this is out of the way,
have you given any more thought to a new edition of Professional Photoshop?
Not to keep up with the constantly changing versions, but because
your innovative and often controversial techniques using the old tools are
quite a stimulus to continued experimentation. It has crossed my mind
that Adobe is attempting to keep up with your new ways of doing things with
old tools by creating new tools to do much the same thing.
On the other hand I realize that
book-writing is not the most profitable pursuit in the world, its monetary
worth being inversely proportional to the amount of time and effort
put into the writing the book in the first place. But we can hope.
We can hope, can't we?
Howard Smith
___________________________________________________________________________
Date: Tue, 26 Jul 2005 15:50:14 EDT
From: Dan Margulis
Subject: Re: Professional Photoshop
I have always intended a new version of Professional
Photoshop in 2006. I have just started to sketch out what will change and
what will be added, and to assemble images that might be useful. But I want
to wait and see how the LAB book is received before making final decisions.
Each edition of the book has had at least 60% new
content. Stuff gets rotated out as it ages. The current edition's
discussion of sharpening and its introduction to channel blending both date
from 1998 and will certainly be upgraded. The sharpening chapter is still
very sound so I expect I will simply add another chapter that discusses
alternate methods and relates it to the use of Shadow/Highlight. The
channel blending IMHO now needs to be redone from scratch.
As always, we will react to how workflows have changed
between editions. So there will certainly be discussions of Camera
Raw and also of the implications of high-quality desktop printing, which
was much less of a factor in 2002 when the last edition appeared than it is
today.
Dan Margulis
___________________________________________________________________________
Date: Tue, 26 Jul 2005 19:40:15 -0500
From: "drhobbes"
Subject: Re: Professional Photoshop
Good! Good! Good! That information brightened my
day! You might also consider publishing a collection of your EP
articles, both for historical and educational reasons. Even your first
book, Makeready, was well worth the search. While of course you
covered many of the same things in Professional Photoshop, the way you
explained them in Makeready gave me a new way of looking at color
correction that in turn led to development of some valuable new techniques
that may never have occurred to me otherwise.
As for the new book on LAB, it will be a rousing
success. You can stop worrying about that now and start writing the
new edition of Professional Photoshop.
You may be controversial, Dan, but we're sure glad you
didn't step backward into that hole in Hawaii.
Howard Smith
___________________________________________________________________________
Date: Fri, 12 Aug 2005 06:48:08 -0400
From: Michael Cervantes
Subject: RE: Digest Number 1508
Nobody knows
how well a book on LAB will sell--it's uncharted
territory. So the publisher
is guessing on how many to print, and guessing on how
many to bring to
Photoshop World.
Coming from you, it is going to sell well. You should
bring several boxes to Photoshop World.
Congratulations! I wish you a great success to your
new book.
Best regards
Michael Cervantes
MC Design Studio
___________________________________________________________________________
Date: Fri, 12 Aug 2005 13:33:25 +0200
From: "Francisco Bernal"
Subject: Re: Digest Number 1508
Well, I want one, so at least, you know: count
another.
:-)
/*--------------------------------------*/
Francisco Bernal Rosso
Luz-color-fotografia
Redacción y traducción
___________________________________________________________________________
Date: Fri, 12 Aug 2005 14:20:04 EDT
From: Dan Margulis
Subject: Publication Announcement: The Canyon
Conundrum
It is a pleasure (and a relief) to announce that the
official publication date of my new book on LAB was Monday, August 8. The
title is Photoshop LAB Color: The Canyon Conundrum and other adventures in
the most powerful colorspace (ISBN 0-321-35678-0). It's 384 pages in an
8x10 format. Price is $54.95. It's the first entirely new title I've
published in eight years.
PDFs of the Table of Contents and Chapters 2 and 9 are
posted at http://www.ledet.com/margulis/articles.html
The book is currently available at www.peachpit.com if
you scroll through the authors list--it has not yet entered the search
database. It should be available imminently at amazon.com, and will be
shown at Photoshop World in Boston.
Handled with care, LAB maneuvers are extraordinarily
powerful, often achieving effects that are not even possible AFAIK in other
colorspaces. LAB is not, however, particularly user-friendly. I set out to
write something that would be at least somewhat accessible to non-advanced
users, while at the same time catering to professional-level retouchers and
color specialists.
Therefore, each of the first six chapters is cut in
half. The first halves are quite gentle IMHO. All commands are spelled out.
The basics of an LAB workflow are developed. While there is some general
discussion of under what circumstances you would want to use LAB or to
avoid it, in these first halves I simply state that certain LAB methods
work better than their RGB equivalents and leave it at that. The idea is to
offer something that will give the inexperienced user striking results
immediately, and a sharp improvement in color quality.
In the second halves (and in the final ten chapters of
the book) the discussion gets more technical and there are many comparisons
showing when LAB works better (or worse) than other alternatives.
Some top experts have seen drafts and offered mildly
positive comments. David Biedny, the principal author of Photoshop Channel
Chops and one of the great retouching authorities, contributed a foreword
in which he called the book "the most deeply advanced, inspiring,
insightful, maddening, awesome, demanding, and illuminating educational
effort--in any media format--ever created for Photoshop."
Scott Kelby, who sells more books on Photoshop than
anybody else, also had a read. His comment: "This book is going
to radically change how we all do color correction from this point on.
Anyone not using the techniques Dan unveils in this book will soon be a
digital dinosaur. It's that revolutionary."
More down-to-earth feedback came from a dedicated
group of seven beta readers selected from this list, a group of very
diverse backgrounds and skill levels. They caught a slew of unclear areas
and offered many useful suggestions. If you like the book, you owe thanks,
as I do, to Les De Moss, Andre Dumas, Bruce Fellman, Timo Kirves, Katia
Lazarova, Clarence Maslowski, and Clyde McConnell.
Also, I'd like to thank the many list members who
offered images for inclusion. Particularly, I'd like to thank those who,
after discussing what I was after, were kind enough to send me a selection
of *several* images. They are David Barr, Jim Bean, Michael Benford, Hunter
Clarkson, Mike Demyan, Fred Drury, Jason Hadlock, Mark Laurie, David
Leaser, Mike Russell, Marty Stock, Lee Varis, and Michael Vlietstra. I was
looking for pictures that would best illustrate the potential of LAB, and
it was critical that there be a good variety to choose from. Therefore, not
every one of these people is represented in the book. However, each one of
them made a significant contribution just by presenting alternatives, and
the book is better because of them.
Here's a rundown of the contents.
1. THE CANYON CONUNDRUM
The basic LAB correction method is explained through a
series of images of canyons.
2. LAB BY THE NUMBERS
How LAB is structured, what the numbers mean, how they
interrelate with one another to create colors, and how they relate to the
human visual system.
3. VARY THE COLOR, VARY THE RECIPE
The basic recipe of Chapter 1--an overall color
enhancement--can be approximated in RGB, although the results will not be
as good. When the A and B curves run at different angles, though, the
result is unique to LAB.
4. IT'S ALL ABOUT THE CENTER POINT
Using LAB to eliminate color casts.
5. SHARPEN THE L, BLUR THE AB
LAB often, but not always, has a significant
sharpening advantage over RGB, even when the RGB sharpening is done in
Luminosity mode. When an image needs to be blurred, LAB is much better than
RGB/Color mode. This chapter explains not just how but why, covering a lot
of ground that is not well understood.
6. ENTERING THE FOREST: MYTHS & DANGERS.
Some avoid the use of LAB based on myths, which are
debunked here. On the other hand, certain features of LAB are in fact
rather dangerous if the user is not careful.
7. SUMMING UP: LAB AND THE WORKFLOW
The first half comes to a close with a discussion of
when and why to use LAB, a question to which different users will come up
with different answers. Only those who are extremely pressed for time would
want an all-LAB workflow. Everyone else needs a disciplined approach to
when to use it.
8. THE IMAGINARY COLOR, THE IMPOSSIBLE RETOUCH
LAB permits us to designate (at least theoretically)
colors that could not possibly exist, such as a brilliantly red black.
Doing so doesn't sound particularly intelligent, but using imaginary colors
can be an extraordinarily powerful retouching tool.
9. THE LAB ADVANTAGE IN SELECTIONS AND MASKING
The best masks usually use a single channel as a base,
but few people think of using the A or B for that purpose. In fact, those
channels can make selections appear out of thin air--and in one spectacular
example, they make a selection *of* thin air.
10. THE PRODUCT IS RED BUT THE CLIENT WANTS GREEN
The most effective way of making major color changes
away from the art, as when the photograph portrays a product in one color
but the client specifies not just another color but gives a PMS number to
match.
11. THE BEST RETOUCHING SPACE
David Biedny, who is one of the world's most skilled
retouchers, calls this chapter "nothing short of astounding."
12. COMMAND, CLICK, CONTROL
A chapter on advanced LAB curving that was one of the
favorites of the beta readers.
13. THE UNIVERSAL INTERCHANGE STANDARD
We take a break from Photoshop technique to discuss
LAB's role in the exchange of documents from one colorspace to another, and
also see how the difficulties of setting up a conversion of out LAB suggest
solutions for other kinds of color-matching issues, such as making CMYK
matches to Pantone colors.
14. ONCE FOR COLOR, ONCE FOR CONTRAST
Four examples, one each of curves and of blends in
Luminosity and Color modes. When should they be done in LAB, and when in
RGB?
15. BLENDING WITH THE A AND B
The most difficult chapter of all considers blending
the A and B channels into each other and/or the L for gains in contrast and
color intensity.
16. A FACE IS LIKE A CANYON
We end the adventure with an easy, yet spectacular
recipe for improving the believability of face shots, illlustrated
step-by-step with five individuals of various ages and ethnicities.
This book took a lot more effort than I really would
have liked. Unlike Professional Photoshop, every chapter was completely
new. Also, because so many of the techniques are bleeding-edge, they
haven't been studied much, and I was learning as I went along. I am pleased
with the results and think that almost everyone will find some powerful new
tools and significant improvements for their own workflow.
As previously announced, I plan a new edition of
Professional Photoshop in 2006. It will certainly vary considerably from
the current edition, but a lot will depend on what the reaction to this LAB
book is.
Dan Margulis
___________________________________________________________________________
Date: Fri, 12 Aug 2005 15:04:23 -0700
From: Glenn Huish
Subject: Re: Re:_Boston_Photoshop_Conference, LAB
book?
Dan Margulis wrote:
Nobody knows
how well a book on LAB will sell--it's uncharted
territory. So the publisher
is guessing on how many to print, and guessing on how
many to bring to
Photoshop World.
heh. this is so true, i never really thought about it.
well, i'm already good for one, now if amazon just
gets it out the door...
Glenn A. Huish
Chief Technical Officer
Bel Aire Displays
5710 Hollis St.
Emeryville, CA 94608
510.654.0964 x27
http://www.belairedisplays.com
___________________________________________________________________________
Date: Sat, 13 Aug 2005 10:41:36 -0400
From: Patrick Chuprina
Subject: Re: Publication Announcement: The Canyon
Conundrum
Congratulations! Now to wait the the 4 to 6
weeks Amazon.ca says it takes to ship. I'm really looking forward to
this.
Patrick Chuprina
___________________________________________________________________________
Date: Sun, 14 Aug 2005 00:56:36 -0700
(PDT)
From: dimitrij saherl
Subject: Re: Publication Announcement: The Canyon
Conundrum
Best wishes with the new book. It¨s a brilliant.
/based on chapter 2 and 9, articles in Photoshop user./
Regards, dimitrij
dimitrij saherl
www.av-studio.si
___________________________________________________________________________
Date: Mon, 29 Aug 2005 18:10:13 -0000
From: "hfdomke"
Subject: Eighteen Questions about Dan's new LAB book
Questions from Henry Domke on Dan Margulis's book:
"Photoshop LAB Color, The Canyon Conundrum and Other Adventures in the
Most Powerful Colorspace"
The first 8 questions are my main questions. Questions
9 through 18 are more minor questions and observations.
1. Why be so opposed to selections? The entire book
seemed excessively focused on global corrections.
2. How does one manipulate the red-cyan axis in LAB?
How is it buried in the AB channels?
3. Does Adobe Capture RAW run on LAB? It too has no
control for the red-cyan axis. Isn't the temperature slider really a
"B" slider (yellow-blue) and the tint slider the "A"
slider (magenta-green)?
4. Chapter Six: "In the last three years, around
a dozen people, including me, have made serious efforts to find anything to
support the proposition that 16-bit editing might be better under any
circumstances. … nobody has found any quality gain at all." This
is certainly provocative and counter-intuitive. What do other respected
authors have to say about this topic? Say the authors of Real World
Photoshop?
5. If we enhance color variability somewhere by
increasing the slope of the curve does that mean we loose it somewhere
else? This is true with contrast adjustments using curves in other color
spaces.
6. Why on earth doesn't Dan use layer masks for some
of his corrections? With today's fast processors and cheap memory, layer
masks are very fast and can be revised. One thing with his techniques is
that you had better get it perfect the first time or go back and start from
the beginning. What about the mantra of many Photoshop gurus who say: never
do destructive editing, always leave yourself an out. His methods almost
always are irreversible. Comment?
"Too many people use selections as crutches. The
better you get at image manipulation, the less you make them." P. 182
and his comment on p. 189 "Creating a selection is for those who are
certain they know what they want. Making a mask is for those who want room
to experiment." Your bias here is not my experience. I
have been using Photoshop since version one. For years I have used it every
day on thousands of images. I have found that specialized selections (layer
masks that I paint on with a Wacom tablet) provide fast and realistic
manipulation. It allows me to change opacity later, or even go back and
change the settings on the Adjustment layers. The painting in layer masks
is very intuitive. I use Actions to create masks such as: Contrast, Darken,
Lighten and Boost Saturation. I just apply them where I want. Have
you ever give a serious look at that workflow? What is wrong with
experimenting (as you say) anyway?
7. On page 106: Photoshop's Camera RAW plug-in
has a setting to control it but "working the AB is a more elegant and
effective solution". Is that still true with Photoshop CS2? Isn't
"Luminance smoothing" simply blurring the L channel and Color
Noise Reduction simply blurring the AB channels? Is this another example of
LAB being behind the scenes in Capture RAW plugin?
8. On page 114 Dan writes "We haven't used
selections or masks yet in this book. They'll rear their ugly heads at the
end of Chapter 7. Most people overuse them." What makes you say that?
You seem almost pathologically averse to considering using Adjustment
layers which have associated masks as fully explained in Real World
Photoshop CS. Why?
9. Why do the A and B channels range from 127 to
minus128? Why aren't they the same number?
10. Most of the illustrations in the book are
remarkably clear and demonstrate what is being discussed. However, I think
Figure 8.13 is a poor example. To my eye the line separating the blue sky
and the blue mountains is too pronounced and fake looking
11. In Chapter 6 he writes: "Standard deviation
can also be part of image analysis. Like the histogram I consider it
worthless as an aide to image manipulation. Neither can tell us about the
visual quality of an image as accurately as our own eyes do". Isn't
this a bit harsh? "Worthless"? Not to me. Many Photoshop users
find looking at histograms critical. Have we clipped the image? Do we have
adequate tonal range?
12. Most of the book seems to be a pep talk about all
the great things about LAB. He doesn't spend much time talking about the
downsides of LAB. For example in LAB the following does not work:
1. Adjustment Layers: Selective Color, Channel Mixer
2. Filters: Several (although USM and the blur
filters do work).
3. 32 bit color
13. You caution about using LAB in any other program
than Photoshop. I noticed that in Adobe's Creative Suite Professional CS2
that at least two programs could work with LAB. InDesign and Acrobat 7
Professional. Would they not print properly?
14. There must be some relation to saturation and
color variability, yes? Steepening the curves in AB clearly have increased
saturation as one of their attributes, yes? You can't increase color
variability without increasing saturation, can you?
15. Dan states in Chapter 5: "Deciding whether an
image has a cast is probably the most difficult task in color
correction." If this is true, then should professional
photographers make it a rule to always shoot a grey card? How much would
that help?
16. Wouldn't it better to do all LAB curves on an
Adjustment layer? For one thing you can only do one curve per channel in
Lab, they don't all pop down like in RGB. Furthermore, you can very opacity
of the layer if you wish, after the fact.
17. Chapter 5: "Focus is a question of luminosity
variation, not color. Noise is color only, with little change in
luminosity". What about film grain, that has luminosity variation
also, yes? You must just be referring to digital capture only.
18. What is your take on the two-step sharpening
process advocated by the folks at PK Sharpener Pro? They propose applying a
"Capture Sharpening" which is applied early on in the sharpening
process. It's aim is to restore sharpness lost during the capture
process. This book (and common sense) advocates that sharpening occur near
the end of your Photoshop work. www.pixelgenius.com
Thanks,
Henry F. Domke
Henry Domke Fine Art
www.henrydomke.com
____________________________________________________________________________
Date: Mon, 29 Aug 2005 15:49:47 -0600
From: Andrew Rodney
Subject: Re: Eighteen Questions about Dan's new LAB
book
On 8/29/05 12:10 PM, "hfdomke" wrote:
3. Does Adobe Capture RAW run on
LAB? It too has no control for the
red-cyan axis. Isn't the temperature slider
really a "B" slider
(yellow-blue) and the tint slider the "A"
slider (magenta-green)?
No, not at all. The RAW file is a Grayscale data file.
ACR converts this (demosicing) into a linear encoded (gamma 1.0) ProPhoto
RGB color space and from there, into one of it1s four supported RGB working
spaces.
7. On page 106: Photoshop's
Camera RAW plug-in has a setting to
control it but "working the AB is a more elegant
and effective solution". Is
that still true with Photoshop CS2? Isn't
"Luminance smoothing" simply blurring the L
channel and Color Noise Reduction simply blurring the
AB channels? Is this another example of LAB being behind the scenes in
Capture RAW plugin?
No, ACR doesn1t touch LAB in any way although I can
ask Thomas Knoll if his two proprietary camera profiles make a call to
CIEXYZ (it wouldn1t be LAB).
18. What is your take on the
two-step sharpening process advocated by
the folks at PK Sharpener Pro?
We actually propose a three step process, the middle
is creative sharpening which is totally optional. The workflow is discussed
here:
http://www.creativepro.com/story/feature/20357.html
Andrew Rodney
____________________________________________________________________________
Date: Tue, 30 Aug 2005 12:06:18 -0400
From: Lee Clawson
Subject: Re: Eighteen Questions about Dan's new
LAB book
on 8/29/05 2:10 PM, hfdomke awrote:
Henry,
With all due respect to Dan I'll give you some idea
how I see this stuff......
I'll preface my comments by saying that a lot of your
questions seem to be about workflow, that is, which workflow works best in
a given situation. In our studio there's more than one, changing with the
needs of the work.
Lee
________________________
1. Why be so opposed to selections? The
entire book seemed excessively
focused on global corrections.
I don't like making them either. They're tedious and
can take too long.
5. If we enhance color variability
somewhere by increasing the slope of the
curve does that mean we loose it somewhere else? This
is true with contrast
adjustments using curves in other color spaces.
I assume this happens, that is, "we loose it
somewhere else". What's lost usually doesn't bother me in comparison
to what's gained.
6. Why on earth doesn't Dan use layer
masks for some of his corrections?
.......methods almost always are irreversible.
Comment?
"Too many people use selections as
crutches..........I have found that
specialized selections (layer masks that I paint on
with a Wacom tablet)
provide fast and realistic manipulation........
Have you ever give a serious look at that workflow?
What is wrong with experimenting (as you say) anyway? I have no problem
with your work flow. I don't work like Dan does either. I rarely use layer
masks. I think it has a lot to due with how or when you learned color
correction. Please keep in mind this has been done without a computer and
it's inherent reversibility for a long, long time. (Add the same comments
to question #8 too)
10. Most of the illustrations in the book
are remarkably clear and
demonstrate what is being discussed. However, I think
Figure 8.13 is a poor
example. To my eye the line separating the blue sky
and the blue mountains
is too pronounced and fake looking
One image is off, egads!!! -- You should spend a day
in our studio.
11. "Standard deviation can also be
part of image analysis...the histogram
I consider it worthless ...... Isn't this a bit harsh?
"Worthless"?
Not to me. ....Have we clipped the image? Do we have
adequate tonal range?
Haven't used the histogram either. I think it's useful
for calibration tasks but having the answers it provides doesn't help me
when looking at what I want from an image.
13. You caution about using LAB in any
other program than
Photoshop.....Would they not print properly?
I don't know of a RIP that would do the on-the-fly
conversions.
____________________________________________________________________________
Date: Tue, 30 Aug 2005 12:06:15 -0600
From: Andrew Rodney
Subject: Re: Eighteen Questions about Dan's new
LAB book
On 8/30/05 10:06 AM, "Lee Clawson"
wrote:
13. You caution about using LAB in any
other program than
Photoshop.....Would they not print properly?
I don't know of a RIP that would do the on-the-fly
conversions.
ImagePrint can.
Andrew Rodney
____________________________________________________________________________
Date: Tue, 30 Aug 2005 12:58:13 -0600
From: Andrew Rodney
Subject: Re: Eighteen Questions about Dan's new
LAB book
On 8/30/05 12:44 PM, "Henry Domke"
wrote:
I have always beenÊuncomfortable with the conceptÊof
two (or three-step)
sharpening.ÊSharpening always alters the image by
accentuating edge contrast.Ê
How else would you sharpen an image?
The sharpening is all layer based so unless and until
you flatten, the underlying data is never affected. All the sharpening is
done using complex masks on the actual pixel data. This is something that
can1t be done globally and is ideally done in Photoshop. Masks allow the
protection of areas that should not undergo sharpening. For example, smooth
shadows which when sharpened would increase noise. A mask allows one to
decide what edges get sharpened, where in the tonal scale, how smooth etc.
You can do all this manually but then you need to know what values to plug
in for the capture device (how much sharpening is needed to over come the
digitizing process) and then how much for the output device. That secondary
sharpening has to understand the first sharpening process or it1s too
little or too much.
If one does this early on during image preparation, I
fear that some
manipulation, especially enlargement, will accentuate
this sharpening
artifact.Ê
This is why output sharpening is done at output
resolution since of course, this is resolution dependant. Capture
sharpening is too but its VERY subtle and is only used to produce a good
master for all additional sharpening. This is a lot like your RGB working
space master in which you can apply any number of output profiles for the
output needs.
Many of my prints are sold very large. For example I
am preparing a 10x60 foot
mural today.
And output sharpening would be applied based on that
exact size to the device you tell us you want to send the pixels to. That1s
why you need different settings for halftone based on a linescreen versus
an ink jet versus a contone printer. Size AND output device needs to be
defined. If you decide you want to print at half that size, you go back to
the original 3master2 with it1s capture sharpening, size and then sharpen
for a specific output device at that specific size. The capture sharpening
will be 3correct2 for either size since the big sharpening moves are all
output.
Have you done A-B comparisons with images greatly
enlarged (20 x 30 inches and
much larger) to see if two-step sharpening is actually
better then sharpening
near the end?Ê
Yes! And so can you with the demo which is fully
functional for 7 days.
By-the-way, I own PK Sharpener Pro and do use it some,
but I never do the
capture sharpen
You should because the output sharpening is assuming
the file has undergone capture sharpening and was designed for that in
mind. Now you don't have to but that's how the workflow was designed. Why
not do that (it will be on a layer) apply output sharpening and print with
the capture layer on and off.
Andrew Rodney
____________________________________________________________________________
Date: Tue, 30 Aug 2005 13:44:51 -0500
From: Henry Domke
Subject: Re: Eighteen Questions about Dan's new
LAB book
Andrew,
First, I should tell you that your new book
"Color Management for Photographers" arrived today from Amazon. I
am really looking forward to reading it.
You responded to my question:
We actually propose a three step process, the middle
is creative
sharpening which is totally optional.
I have always been uncomfortable with the concept of
two (or three-step) sharpening. Sharpening always alters the image by
accentuating edge contrast. If one does this early on during image
preparation, I fear that some manipulation, especially enlargement, will
accentuate this sharpening artifact. Many of my prints are sold very large.
For example I am preparing a 10x60 foot mural today.
I prefer to do all my image manipulation at my cameras
native resolution(4992 x 3328 pixels with my Canon 1Ds Mk2) Since I sell
prints of many sizes I prefer to do my sizing just before printing and it
is after sizing the image that I typically do my once and only sharpening
with USM.
Have you done A-B comparisons with images greatly
enlarged (20 x 30 inches and much larger) to see if two-step sharpening is
actually better then sharpening near the end? I fear that most of your
users output to print publications and that the images are much smaller. My
needs may be different.
By-the-way, I own PK Sharpener Pro and do use it some,
but I never do the capture sharpen.
Talk to you soon,
Henry
Henry Domke Fine Art
www,henrydomke.com
____________________________________________________________________________
Date: Tue, 30 Aug 2005 22:37:42 EDT
From: Dan Margulis
Subject: Re: Eighteen Questions about Dan's new LAB
book
Henry Domke writes,
1.  Why be so opposed to
selections? The entire book seemed
excessively focused on global corrections.
Chapter 9 is titled "The LAB Advantage in
Selections and Masking". In subsequent chapters, particularly Chapters
11 and 16, there is extensive coverage of masking and of layer Blend If
options, a sophisticated form of selection.
2.  How does one manipulate
the red-cyan axis in LAB? How is it buried
in the AB channels?
This is explained in the second half of Chapter 4. Red
is defined as positive A, positive B. Cyan is negative A, negative B.
3.  Does Adobe Capture RAW
run on LAB?
No.
4.  Chapter Six: "In
the last three years, around a dozen people, including me,
have made serious efforts to find anything to support
the proposition that
16-bit editing might be better under any
circumstances. ... nobody has found any quality
gain at all." This is certainly provocative and
counter-intuitive. What do other respected
authors have to say about this topic? Say the authors
of Real World Photoshop?
At present there is to my knowledge no person in the
world claiming to possess any real-world color photograph, to which any
series of real-world corrections were applied, where the results are any
better when done in 16-bit than in 8-bit. Many people, on the other hand,
have run tests in which absolutely massive corrections have been applied,
far beyond anything that would ever be done in the real world, and there is
no evidence at all of any advantage. New examples are shown, at high
magnifications, in Chapter 6. At this point the evidence is overwhelming
that there is no 16-bit advantage in dealing with color photographs. A few
people argue otherwise, but it has now become a matter of religious belief,
rather than reliance on demonstrations that they can't provide.
With respect to the author you mention, in a recent
thread on the ColorSync list I repeatedly asked him whether he had ever
personally run a test (or seen anyone else perform such a test) where the
same exact corrections were applied in both 8- and 16-bit modes to a
real-world color photograph, and compared the results. He repeatedly
refused to answer.
5.  If we enhance color
variability somewhere by increasing the slope
of the curve does that mean we loose it somewhere
else? This is true with contrast
adjustments using curves in other color spaces.
It is true in the L channel but not in the A and B,
because a substantial area of each curve covers colors that are not in use.
There are certain cases where one *wishes* to lose color variation but
there is no need to do so.
6.  Why on earth doesn't Dan
use layer masks for some of his
corrections?
According to the index, there are discussions of layer
masking on pages 176-178, 192-194, 206-208, 220, 223, 225. The very image
that you complain about in item #10 below is prefaced by a lengthy
discussion of how to make a layer mask, and the layer mask itself is shown
as a separate graphic in Figure 8.11.
One thing with his techniques is that you had better
get it perfect the
first time or go back and
start from the beginning. What about the mantra of
many Photoshop
gurus who say: never
do destructive editing, always leave yourself an out.
His methods
almost always are irreversible. Comment?
The book is not about how to use the history palette,
or about when and how often to save intermediate backup files, or about how
layers are appropriately used in Photoshop documents. It is about how LAB
functions. We have to assume that each reader will use a workflow that is
sufficiently flexible to meet his own objectives.
"Too many people use selections as crutches. The
better you get
at image manipulation,
the less you make them." P. 182 and his comment
on p. 189
"Creating a selection is for
those who are certain they know what they want. Making
a mask is for
those who want
room to experiment."Â Â Your
bias here is not my experience.Â
The chances are that your experience is based only on
comparisons of your own images with your own images, whereas I've had the
opportunity to watch people use the selection-first method in competition
on the same image with others who don't. Remember, I've trained well over a
thousand people intensively, meaning over periods of several days or more.
Those people who use selections as a first rather than a last resort
consistently achieve lower-quality results than their colleagues, and they
invariably state afterwards that they realize they should not have been
selecting as much as they had.
I also have the opportunity to observe advanced
classes, where the average student is approximately as good as I am in
color correction, and where they have had months if not years to apply and
experiment with what they have learned in the first class. It is absolutely
clear that as people become more skilled in color correction they make
fewer selections.
7.  On page 106:Â
Photoshop's Camera RAW plug-in has a setting to
control it but "working the AB is a more elegant
and effective solution". Is
that still true with Photoshop CS2? Isn't
"Luminance smoothing" simply blurring the L
channel and Color Noise Reduction simply blurring the
AB channels?
No, it's doing the arithmetic in RGB and then
attempting to revert to luminosity or color afterward. As discussed in
Chapter 5, "Sharpen the L, Blur the AB," there is a decisive
advantage to doing color blurs in LAB rather than RGB/Color mode. Plus, the
blurring tools in Camera Raw are much cruder than those found in Photoshop
proper.
8.  On page 114 Dan writes
"We haven't used selections or
masks yet in this book. They'll rear their ugly heads
at the end of Chapter 7. Most people overuse them." What makes you say
that?
See #6 above.
You seem almost pathologically averse to considering
using
Adjustment layers.
According to the book's index, adjustment layers are
discussed, always positively AFAIK, on pages 115, 152, 193-195, 206, 222,
243, 298, 326. Many of the screen captures showing layer structure in this
book indicate that there were adjustment layers in the document.
9.  Why do the A and B
channels range from 127 to minus 128? Why
aren't they the same number?
Because, as explained in the box on Page 98, a channel
must have exactly 256 discrete values, but zero is a possible value,
leaving an odd number to be divided in half.
10.  Most of the
illustrations in the book are remarkably clear and
demonstrate what is being discussed. However, I think
Figure 8.13 is a poor example. To
my eye the line separating the blue sky and the blue
mountains is too pronounced and
fake looking
As indicated in the text, in real life a retoucher
would likely substitute a real sky from another picture rather than trying
to create one using imaginary colors in LAB. In any case the transition is
less pronounced than in the original.
11.  In Chapter 6 he writes:
"Standard deviation can also be part
of image analysis. Like the histogram I consider it
worthless as an aide to image
manipulation. Neither can tell us about the visual
quality of an image as accurately as our own eyes do". Isn't this a
bit harsh?
No, it's probably too generous. Histograms can be
useful in after-the-fact analysis of an effect, as, for example, in showing
why sharpening in LAB sometimes works better than in RGB/Luminosity. They
can be useful in image capture, where the objective is not to make a
perfect image but to make sure that nothing is lost. In color correction,
they are actually worse than useless when people rely on them rather than
their own eyes. The question is not whether anything is clipped but whether
anything SIGNIFICANT is clipped. Histograms can't answer this question.
12.  Most of the book seems
to be a pep talk about all the great
things about LAB. He doesn't spend much time talking
about the downsides of LAB.
The title of the book, "The Canyon
Conundrum", refers to the question of why LAB does so well on certain
categories of image (e.g. canyons) and not so well on others. The purpose
of Chapter 6, "Entering the Forest, Myths and Dangers" is to
explore not just misconceptions about LAB, but also when to avoid using it.
Most of Chapter 7 is devoted to discussing what types of operation should
be done in LAB and what types at other times in the workflow. The entirety
of Chapter 14 discusses how to identify pictures that are better handled in
RGB than in LAB, and vice versa.
13.  You caution about using
LAB in any other program than Photoshop.
I noticed that in Adobe's Creative Suite Professional
CS2 that at least two
programs could work with LAB.
InDesign and Acrobat 7 Professional. Would they not
print properly?
Not reliably, as explained in Chapter 6.
14.  There must be some
relation to saturation and color variability,
yes? Steepening the curves in AB clearly have
increased saturation as one of their
attributes, yes? You can't increase color variability
without increasing saturation, can you?
Yes. In LAB, often the variation is created by
saturating one color and desaturating a highly similar one, as described in
Chapter 12.
15. Dan states in Chapter 5: "Deciding whether an
image has a
cast is probably the most difficult task in color
correction."Â If this is true, then
should professional photographers make it a rule to
always shoot a grey card? How much would that help?
It would be useful in many cases.
16.  Wouldn't it better to
do all LAB curves on an Adjustment
layer?
No, and there's nothing LAB-specific about this topic.
Some people need the flexibility of adjustment layers and others don't.
Many if not most users intend to output once only, and never correct again.
It's pointless for them to waste time with extra documents, no matter what
colorspace they work in.
17.  Chapter 5: "Focus
is a question of luminosity variation, not
color. Noise is color only, with little change in
luminosity". What about film grain, that
has luminosity variation also, yes? You must just be
referring to digital capture only.
Amazing how the omission of only one word can change
the entire meaning of a phrase. The actual quotation, with the omitted word
capitalized, reads as follows: "Focus is a question of luminosity
variation, not color. Noise is OFTEN color only, with little change in
luminosity." The word "often" does not mean
"always". It does not mean "almost always". It does not
mean "most of the time", or "usually".
18.  What is your take on
the two-step sharpening process advocated by
the folks at PK Sharpener Pro?
I am not familiar with it, sorry.
Dan Margulis
____________________________________________________________________________
Date: Tue, 30 Aug 2005 22:37:58 EDT
From: Dan Margulis
Subject: You're Number One
For those following such things, the publisher
interrupted my vacation today with the news that as of this morning the LAB
book was the #1 selling amazon.com title in the entire computer/internet
field. This is totally surprising since the official rollout of the book
isn't until Photoshop World next week. Its ranking is about #50 in all
books that amazon.com sells.
I would like to again thank the list members who
encouraged this project from the beginning. A lot of people had serious
doubts that people would buy a book on such a limited topic. If it hadn't
been for the feedback from the list, I wouldn't have begun it.
Dan Margulis
____________________________________________________________________________
Date: Tue, 30 Aug 2005 21:36:07 -0700
From: Christopher Zsarnay
Subject: Re: You're Number One
Dan,
Congratulations on the sale of the book.!! I
just received my copy today and I'm looking forward to diving in.
Thanks for writing it.
Chris
Christopher Zsarnay
Z Studios Photography
805-644-5554
http://www.zstudios.com
AIM & IChat: czsarnay
____________________________________________________________________________
Date: Wed, 31 Aug 2005 07:24:24 -0500
From: "Henry Segalini"
Subject: Re: You're Number One
Congratulations.
This list has been very helpful and informative to me.
I'm glad you got something from it as well.
Henry Segalini
Universal Printing
St. Louis MO
____________________________________________________________________________
Date: Wed, 31 Aug 2005 09:32:35 +0100
From: Martin Bailey
Subject: Re: Eighteen Questions about Dan's new
LAB book
At 19:06 30/08/2005, Andrew Rodney wrote:
ImagePrint can.
If the Lab ends up in a PDF file, then any RIP that
claims to fully support PDF should be able to. If it's in a PostScript or
EPS file then it's actually encoded as a normal color space array (CSA), so
any PostScript Level 2 or later RIP should handle it.
Of course, the quality of the conversions probably
varies between implementations.
Thanks
Martin Bailey
-------------------------------------------------------------
Senior Technical Consultant
+44 1223 873800
Global Graphics Software
http://www.globalgraphics.com
Developers of Harlequin & Jaws RIPs and
Jaws PDF Technology
-------------------------------------------------------------
If my views didn't usually coincide with those of my
employer
I wouldn't want to work here, but I am not a
spokesman for
Global Graphics Software
and the buck stops
with me for what I say.
-------------------------------------------------------------
____________________________________________________________________________
Date: Wed, 31 Aug 2005 07:10:54 -0600
From: Andrew Rodney
Subject: Re: Eighteen Questions about Dan's new LAB
book
On 8/30/05 8:37 PM, "Dan Margulis"
wrote:
With respect to the author you mention, in a recent
thread on the ColorSync
list I repeatedly asked him whether he had ever
personally run a test (or seen
anyone else perform such a test) where the same exact
corrections were applied
in both 8- and 16-bit modes to a real-world color
photograph, and compared
the results. He repeatedly refused to answer.
He has an example on page 24 of Real World Camera RAW.
Andrew Rodney
____________________________________________________________________________
Date: Wed, 31 Aug 2005 12:40:25 -0000
From: "hfdomke"
Subject: Response to Margulis's answers my 18
Questions about LAB book
Dan's words are in quotes.
2. How does one manipulate the red-cyan axis in LAB?
How is it buried in the AB channels?
"This is explained in the second half of Chapter
4. Red is
defined as positive A, positive B. Cyan is negative A,
negative B."
But is it possible to manipulate and increase color
variability of Red-Cyan like we can Green-Magenta or Blue-Yellow by steep
curves in the A & B channels? Are there any simple moves we can make to
affect Red-Cyan?
4. "At this point the evidence is overwhelming
that there is no
16-bit advantage in dealing with color photographs. A
few people argue otherwise, but it has now
become a matter of religious belief, rather than
reliance on demonstrations that they
can't provide".
This is a very important issue for all of us that use
Photoshop. Many of us now keep our multi-layered files as 16-bit until we
are ready to print. I have 10,000 files like this and I don't want to
double my storage requirements and slow my processing time by using 16-bit
unless there is clearly a benefit. We need to get a definitive answer.
I am going to start an active web and email campaign
to see if we can get the experts to agree on this. I encourage others to
join me in helping to answer this question decisively. A question with a
look to the future: I have heard some speculation that at some point
printers might support 16-bit files directly. Would that be a case where
there might be some advantage?
6. Why on earth doesn't Dan use layer masks for some
of his corrections?
"According to the index, there are discussions of
layer masking
on pages …"
However, I don't think there is one illustration in
this 366-page book showing a layer mask. Instead, he repeatedly shows
"Blend If" sliders. To my inexperienced way of thinking,
Blend-If is a crippled version of a layer mask. Layer masks on Adjustment
Layers allow you to use gradients, work with variably edged selections,
change opacity and alter blending modes. If you save the layer with
the image, you can go back and tweak it later if the client wants a change.
"The book is not about how to use the history
palette, or about
when and how often to save intermediate backup files,
or about how layers are appropriately
used in Photoshop documents. It is about how LAB
functions."
I never referred to the history palette or
intermediate backup files. However, if one creates their LAB curves on an
adjustment layer, it leaves room to revisit the file for adjustments much
more easily. As my father always said "Keep your options open."
18. What is your take on the two-step sharpening
process advocated by the folks at PK Sharpener Pro?
"I am not familiar with it, sorry."
What kind of answer is that? You have written and
taught extensively on the critical issue of sharpening. I know because I
have read the different editions of your still outstanding
"Professional Photoshop." On page 78 of "Professional
Photoshop 6" you write " Applying a major adjustment to an image
after USM can exaggerate the artifacts of sharpening."
Do you not have an opinion on two (or three) step
sharpening? What do you think of the concept of capture sharpening in
addition to output sharpening? I would guess, based on your writings that
you would argue against it theoretically and would call for examples to
prove it in the "real world."
Lastly, thanks for writing another thought provoking
book. Your thinking and writing style are outstanding. It is fun to
disagree with you.
____________________________________________________________________________
Date: Wed, 31 Aug 2005 10:50:31 +0200
From: Kim Müller
Subject: Re: You're Number One
Congratulation. Still waiting for my copy.
Have you considered making an in depth-book on cmyk
and prep for print? The (out of print) "MakeReady" was maybe such
a book? What about updating it?
Thanks.
Kim Müller
____________________________________________________________________________
Date: Wed, 31 Aug 2005 07:56:44 -0600
From: Andrew Rodney
Subject: Re: Response to Margulis's answers my 18
Questions about LAB book
On 8/31/05 6:40 AM, "hfdomke" wrote:
I am going to start an active web and email campaign
to see if we can
get the experts to
agree on this. I encourage others to join me in
helping to answer
this question decisively.
A question with a look to the future: I have heard
some speculation
that at some point
printers might support 16-bit files directly. Would
that be a case
where there might be
some advantage?
Some already do. If you have an Epson driven by the
ImagePrint RIP, you can use and in some cases see the benefits since it1s
used within it1s proprietary dither.
As for definitive answers, good luck. There are so
many criteria that it1s nearly impossible to get multiple parties to agree
on testing. We also have no idea what output devices will come onto the
scene in a year, let alone 5 or what RIP or driver might utilize the
additional data so if I were you, I1d keep those thousands of files in high
bit. Storage is cheap, all things being equal. You1ve got the data, so keep
it intact.
Andrew Rodney
\____________________________________________________________________________
Date: Wed, 31 Aug 2005 09:23:43 -0700
(PDT)
From: C Sutherland
Subject: Re: You're Number One
Dan,
I've had the book for about 2 weeks- ordered from
Peach Pit as soon as it was announced. It is very, very useful and would
sure recommend it to the list. Not a quick read but didn't expect one.
Congratulations on the success.
Craig Sutherland
____________________________________________________________________________
Date: Wed, 31 Aug 2005 15:41:48 -0400
From: Iliah Borg
Subject: Re: You're Number One
This is the response we got from one of the readers
and followers on dpreview.com :)
"Ignore this ... to your own peril....
I have been finding new ways to PP my shots for years
now....this by far absolutly BLOWS AWAY any PP techniques I have learned to
date.
The reason its so diffrent is it uses Lab Colorspace
which is EXTREEMLY diffrent thean CMYK or RGB...and your photos respond
diffrently...VERY diffrently.
This book is manditory reading to ANYONE who wants
fast PP with no hassles."
Best regards,
ib
____________________________________________________________________________
Date: Wed, 31 Aug 2005 21:17:35 -0400
From: "Gene Palmiter"
Subject: Re: You're Number One
Congrats...I will order mine tomorrow. I would ask
that for future updates you make it clear about the year it came out...I
got the wrong version of Professional Photoshop from Amazon because it
wasn't clear which version was newest. Of course I can see why publishers
might not want to be clear on that...they sold me a book that I wasn't
looking to buy.
Thanks,
Gene Palmiter
(visit my photo gallery at http:
//palmiter.dotphoto.com)
freebridge design group
www.route611.com & Route 611 Magazine
____________________________________________________________________________
Date: Thu, 1 Sep 2005 08:39:48 -0700
From: mac townsend
Subject: Re: You're Number One
Unless you already have it, the previous edition
(which does not focus on LAB beyond a single chapter) should be a good
companion / prerequisite for the LAB book.
Mac Townsend
Adcom Graphics Digital Imaging
Fairfield, California
____________________________________________________________________________
Date: Thu, 1 Sep 2005 12:19:52 -0400
From: John Ruttenberg
Subject: Re: Eighteen Questions about Dan's new LAB
book
Dan Margulis:
At present there is to my knowledge no person in the
world claiming to
possess any real-world color photograph, to which any
series of real-world
corrections were applied, where the results are any
better when done in
16-bit than in 8-bit. Many people, on the other hand,
have run tests in
which absolutely massive corrections have been
applied, far beyond anything
that would ever be done in the real world, and there
is no evidence at all
of any advantage. New examples are shown, at high
magnifications, in Chapter
6. At this point the evidence is overwhelming that
there is no 16-bit
advantage in dealing with color photographs. A few
people argue otherwise,
but it has now become a matter of religious belief,
rather than reliance on
demonstrations that they can't provide.
Without meaning to open this can of worms once again
there is one particular correction for which 16 bit input makes a lot of
sense, at least in theory: highlight/shadow. When starting with raw
input when I know that highlight/shadow will be used to recover either
shadows of highlights, I move the shadow and exposure sliders so that no
clipping occurs and convert to 16 bit format. When stretching for
dynamic range, doesn't it make sense to have deeper pixel data? I
can't say that I have tested this carefully, so I may be wrong. But
there seems to be no harm in this particular piece of workflow and it might
even help sometimes.
____________________________________________________________________________
Date: Thu, 01 Sep 2005 10:35:40 -0600
From: Andrew Rodney
Subject: Re: Eighteen Questions about Dan's new LAB
book
I think it1s important to point out that dynamic range
and bit depth are two totally separate issues/specs.
Like you, when I1m working with high bit RAW data, I
bring this in a bit on the flat side. I know I can move either end closer
to 3clipping2 without introducing any banding. I also know that some
sharpening as well as conversion to an output space can move those points
so I want to start out with some headroom. You could do the same in 8-bit
but you1ve got far fewer steps from say 250 to 255 to set perhaps a
specular highlight. In 8-bit, I1ve got 5 steps. In high bit (which
could be 10/12/14 or 16-bit depending on the capture device), I have a lot
more. So I1m not concerned about setting the ends of the tone scale at the
RAW conversion or scanning stage. I'll work on the master which is a tad
flat, convert (or view a soft proof with the output profile), output
sharpen and see where things lie.
Highlight recovery is different. At least when using
Adobe Camera RAW. It can actually recover lost highlight if you have one
color channel with data. That is, if you1ve blown out (clipped) two color
channels, ACR can reconstruct them from one remaining channel that has
data. As far as I know, this is a unique feature of Adobe Camera RAW and a
pretty useful feature of linear encoded RAW data.
Andrew Rodney
____________________________________________________________________________
Date: Thu, 1 Sep 2005 13:06:06 -0400
From: Henry
Subject: Re: Eighteen Questions about Dan's new LAB
book
Data is not the same thing as printed results.
Before committing to a dogma that insists on always
using 16 bit, it should be for real good reasons that I'm sure 16 bit fans
will offer in reply.
One can put a high performance racing carburetor on a
lawn mower, but it won't do a better job. It will, however, cost
more.
Henry Davis
____________________________________________________________________________
Date: Thu, 1 Sep 2005 10:18:38 -0700
From: Richard Chang
Subject: 16 bit printing
A recently posted question wondered:
A question with a look to the future: I have
heard some speculation
that at some point printers might support
16-bit files directly. Would that be a case
where there might be some advantage?
The bigger question in my mind is how many bits can be
seen (or measured, for that matter) on a reflective rendering?
We can use a traditional reflection densitometer to
derive a D log value for any paper and inks combo. Bits can be
mathmatically related to the D log values. Measurements made by
MegaVision back in the late 80's when they were considering the making of
the first Tessera digital capture device, returned 6.5 bits for a high
performing sheet fed press.
It might be interesting to measure some reflective
targets to see how they perform with today's technically advantaged
rendering methods. Yes, we can send 16 bit files to some devices, but can
we really see a difference between an 8 bit and a 16 bit file on the print?
Just because the driver will accept the 16 bit file, doesn't
necessarily mean that the viewer can see it. It could however, have
marketing advantages to the folks who are selling the technology.
If we consider how many individually seperable tones
we can see reflected from a print, common sense should tells us we should
send a prudent amount more, to make sure we've sent enough. Sending a
16 bit file sounds a lot like printing in 2880, versus 1440. Does
this mean that we're going to have to use the 2880 setting to see the 16
bits?
Richard Chang
____________________________________________________________________________
Date: Thu, 1 Sep 2005 17:40:46 EDT
From: Dan Margulis
Subject: Re: You're Number One
Kim writes,
Have you considered making an in depth-book on cmyk
and prep for print?
My book Professional Photoshop has a fair amount of
such material.
The (out of print) "MakeReady" was maybe
such a book? What about
updating it?
Makeready had some such material, but it was really a
collection of columns on various production-related topics, food for
thought more than a production guide. I may make a new edition of it at
some point, but it is not currently my priority.
I am in the early stages of a new version of
Professional Photoshop, but what's going to be in it definitely needs to be
reconsidered in view of the unexpected results for the LAB book, which, to
the stupification of both myself and the publisher, continues to be the
#1-selling book in the entire computer-related field. So, in the next week
or so, I'll probably be throwing some ideas out for feedback from the
group.
I hope your copy of Canyon Conundrum makes it to
Norway soon.
Dan Margulis
____________________________________________________________________________
Date: Thu, 1 Sep 2005 19:46:58 EDT
From: Dan Margulis
Subject: Re: You're Number One
I would ask that for future updates you make it clear
about the year it
came out...I got the wrong version of Professional
Photoshop from Amazon because
it wasn't clear which version was newest. Of course I
can see why publishers
might not want to be clear on that...they sold me a
book that I wasn't looking
to buy.
Those who were on the list in 2001 may recall that
there was considerable discussion of the titling of this book, all of which
got forwarded to and discussed with the publisher in advance of the final
decision. Coincidentally, the publisher of Canyon Conundrum is not the same
one as that particular version of Professional Photoshop. I think it likely
that future versions of both books, if any, will make clear whether they
are "second edition", "fifth edition" or what.
Dan Margulis
____________________________________________________________________________
Date: Fri, 02 Sep 2005 08:11:13 -0400
From: Ted Lane
Subject: Re: Eighteen Questions about Dan's new LAB
book
At 9/2/2005 05:53 AM, Dan Margulis wrote:
6. At this point the evidence is overwhelming that
there is no 16-bit
advantage in dealing with color photographs. A few
people argue otherwise,
but it has now become a matter of religious belief,
rather than reliance on
demonstrations that they can't provide.
I see the above quote refers to "color"
photographs. Does the same finding hold true for images converted to Black
& White from a color capture?
Thanks for your help,
Ted
____________________________________________________________________________
Date: Fri, 02 Sep 2005 13:13:47 -0000
From: Stephen Marsh
Subject: Re: Eighteen Questions about Dan's new LAB
book
---Ted Lane wrote:
I see the above quote refers to "color"
photographs. Does the same
finding hold true for images converted to Black &
White from a color
capture?
Thanks for your help,
Ted, this has come up in the past. Probably in one of
these two archives, if not it is here, I remember the thread/s.
http:
//www.ledet.com/margulis/ACT_postings/ACT-8-bit-16-bit.html
http:
//www.ledet.com/margulis/ACT_postings/ColorCorrection/ACT-16-bit-2002.htm
The upshot is, that yes, it can in theory help as
there is only one channel, but if I remember correctly, Dan's position is
that the quality gained from making all tonal corrections in the full
colour original before conversion to monotone in 8bpc is the 'correct'
workflow. While most users I encounter would just convert to single channel
mode or mix R==G==B and then use levels/curves - thus they loose the