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
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   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
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   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
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   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
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   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
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   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
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   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
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   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.  Â  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.  Â  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.  Â  Does Adobe Capture RAW run on LAB?
 
No.

4.  Â  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.  Â  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.  Â  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."   Your bias here is not my experience.  
 
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.  Â  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?

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.  Â  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.  Â  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.  Â  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.  Â  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.  Â  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.  Â  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.  Â  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.  Â  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.  Â  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.  Â  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