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CIE LAB anyone?

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  #1  
Old 09-02-2005, 09:24 PM
Rodi Rodi is offline
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CIE LAB anyone?

Hi,
I was wondering, does anyone use LAB in PSD/PHOTO etc? I like it because it keeps the contrast (L) channel separate from the color (AB).

God Bless,
Rodi

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Last edited by Rodi; 09-02-2005 at 09:36 PM.
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  #2  
Old 09-03-2005, 07:41 AM
mdavis mdavis is offline
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Yes, LAB is an excellent color space for doing certain types of editing. There is a new book just out by Dan Margulis called "Photoshop LAB Color". It is one of the most detailed, cutting edge color editing books ever written for Photoshop and is, apparently, the #1 selling Photoshop book at Amazon this week. It has gotten rave reviews from some Photoshop gurus like Scott Kelby and David Beidny (author of the classic "Channel Chops" book).

It would be helpful to have read "Professional Photoshop - 4th Ed." by Margulis before diving into his "LAB", however. This is one "heavy" book that I think will become a classic on a subject largely ignored by other authors.
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Old 09-03-2005, 09:24 AM
skipc skipc is offline
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Lab

The book mentioned is extrodinary. I do all my color correction in LAB and will do more and more as I better understand the possibilities presented ...skip
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  #4  
Old 09-03-2005, 12:30 PM
Rodi Rodi is offline
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Yeah,
I got it and it is superb. Just on quick review it is really a deep book, much more than what I understand. Dan Margulis is also a great writer. You can get his column "MakeReady" for free by subscribing up for Electronic Publishing magazine. He is in 6 issues a year and the subscription is free.

LAB is great because just basic moves enhance many pictures and removes color casts.

God Bless,
Rodi
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  #5  
Old 09-03-2005, 10:10 PM
mdavis mdavis is offline
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Even Margulis cautions that LAB (or any color space for that matter) is not best for all situations. His book "Professional Photoshop 4th Ed." nicely explores RGB, CMYK and LAB and compares the strength and weaknesses of each. In other words, don't always reach for a hammer if a saw works better for what you need to do.
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Old 09-03-2005, 11:00 PM
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Duv Duv is offline
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Perhaps to mdavis point, a considerable body of work has been built over time re RGB grey point corrections, CMYK skin tone corrections. Not having read Margulis' new book, I suspect it still lacks some of the acquired "intuitiveness" of the other spaces. Will it ever have the 1,2,3 relative simpleness? I am awaiting my book with great anticipation but think it may be others who may find a "simple" beauty in working in LAB.

Dave
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  #7  
Old 09-04-2005, 09:02 AM
skipc skipc is offline
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acquired "intuitiveness" [/QUOTE]

Interesting postulation, seems more like applied knowledge. Having actually read the book—on my third reading, it may take twenty—I find LAB as presented therein—offers faster correction, greater control, and endless opportunity for application. No doubt one draws on all Photoshop experience, and it easy to imagine how that knowledge could be ported. A simple Curves adjustment in LAB might require numerous adjustment layers and mask by conventional methods. Then you say, "well what if I added that other stuff on top of this stuff...oh my!" Early days at any rate; no tool fits—or is necessary—for every job, some are just more adaptable...skip
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  #8  
Old 09-04-2005, 02:51 PM
mdavis mdavis is offline
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Any colorspace can be "intuitive" if you learn it, just as Spanish is intuitive in Mexico or English (in its many variations) in the U.S., Australia, G.B. and Canada. Since we all probably learned RGB (or English) first, all else is less than intuitive.

LAB is quite logical, and Margulis make the point that it is actually more like the way we see colors than RGB. All color spaces make use of the color wheel. The only difference is how the information is divided into the grayscale "channels" used to hold color and detail information. We have all probably used the HSB (hue, saturation, brightness) sliders in our imaging editors. LAB is essentially the same idea. The first couple of chapters of "Photoshop LAB Color" give you the basics of HOW to use LAB for color correction. The rest of the book gives you the basics of why it works. Using LAB is very simple. Using it creatively with advanced channel blending and such gets a bit hairy, but no more so than in RGB/CMYK.

So, if you understand the L channel (lightness) and you can understand the relation of colors on the color wheel, you can use LAB curves to do some amazing things that you just can't do in RGB/CMYK. As long as you keep the center of the a* and b* channel curves centered, all remains balanced with respect to color casts. It's a "no brainer" as long as you don't go twisting the curves when you don't need to.
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  #9  
Old 09-04-2005, 09:17 PM
Rodi Rodi is offline
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Hi,
Breaking contrast from color is the strength of LAB and really blowing casts away is relatively simple. Also it is easy to add contrast/color enhancement while keeping the neuterals neuteral.


God Bless,
Rodi
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  #10  
Old 09-16-2005, 10:36 AM
edgework edgework is offline
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Lab

As mentioned already, lab is unmatched for removing color casts. The other thing it does that cannot be duplicated in other spaces is the way it effortlessly pulles hues apart and clarifies them. The only comparable moves in CMYK and RGB are to use Saturation, which is nowhere close.

I started using lab around the time Margulis' "Professional Photoshop" came out for version 5. He had an exercise there that showed how to separate and enance colors, and though I really didn't understand what was going on at the time, I was able to put the technique to good use anyway. He also used a more precise method for removing casts, which he seems to have abandoned in his new book, for a more intuitive approach.

It's not a subtle space. Fine tuning face tones or contrasts can be done much better in CMYK or RGB, particularly if you split up your curves into luminosity mode and color mode, borrowing some of the utility of lab but allowing much fines moves. But when you need a major makeover, nothing comes close.
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