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Is Lab color (L*a*b*) still relevant?

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  • Is Lab color (L*a*b*) still relevant?

    Aside from the occasional "Photoshop secret" tip I rarely see Lab mentioned anymore. Obviously the option is still there, and it works the way it always has, but it used to be touted as the ultimate guru technique.

    Was it a workaround that has since been surpassed by clearer and more direct methods? Or just more of a headache than it's worth? Or do the Lab fans just hang out elsewhere?
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  • #2
    Re: Is Lab color (L*a*b*) still relevant?

    In my opinion these things tend to gain popularity due to edge cases where other algorithms are unstable unstable under certain conditions or may align to produce undesirable results. Converting between color spaces isn't ideal whenever it's avoidable, as you always lose some precision, and it's problematic to preserve layers.

    Do note that edge cases still exist with color correction algorithms. They've just improved quite a bit. For example if you look at brightness/contrast now compared to say photoshop 7, you'll see that the current one applies a scale factor to its channel values. I'm not sure what the old one did, but this certainly results in less color shift. Companies as big as Adobe tend to avoid sweeping changes wherever possible, because it can hurt the ability to access old images. They dealt with that by allowing you to embed a flattened version.

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    • #3
      Re: Is Lab color (L*a*b*) still relevant?

      Originally posted by Doug Nelson View Post
      Aside from the occasional "Photoshop secret" tip I rarely see Lab mentioned anymore. Obviously the option is still there, and it works the way it always has, but it used to be touted as the ultimate guru technique.

      Was it a workaround that has since been surpassed by clearer and more direct methods? Or just more of a headache than it's worth? Or do the Lab fans just hang out elsewhere?
      Photoshop LAB is still there and it still works. A valuable color space that can handle many correction problems quickly and easily. When you don't need it you probably won't miss it, but if you do need it, you'll be glad to have it, if you know how to use it, and know when to use it.

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      • #4
        Re: Is Lab color (L*a*b*) still relevant?

        I think it was Chris Cox in one of my shows, but I'm not going to wade through 6 hours of video to find out, but it was definitely an Adobe engineer that told me that working in Lab was unnecessary effort because Photoshop did everything in Lab behind the scenes anyway.
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        • #5
          Re: Is Lab color (L*a*b*) still relevant?

          Originally posted by Doug Nelson View Post
          Aside from the occasional "Photoshop secret" tip I rarely see Lab mentioned anymore.
          Thank goodness. And if Chris Cox had a show, I'd love to see it. I know Chris dating back to before he was a Photoshop engineer and just a kid. Anyone here recall "Chris's Filters"? The work impressed Thomas Knoll and Adobe hired him up just out of school.

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          • #6
            Re: Is Lab color (L*a*b*) still relevant?

            Originally posted by Doug Nelson View Post
            but it was definitely an Adobe engineer that told me that working in Lab was unnecessary effort because Photoshop did everything in Lab behind the scenes anyway.
            Photoshop probably uses LAB as a profile connection space in their CMM. If adjustments are computed relative to the CMM rather than the RGB space, he would effectively be telling the truth. From a user perspective the behaviors don't really match though.

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            • #7
              Re: Is Lab color (L*a*b*) still relevant?

              Yes, it does use Lab as within it's CMM. But not for much else. There's an old urban legend that PS does 'everything', all operations in Lab, not so. Actual conversions to and from Lab (as you'd do in Mode Change) are too slow and unnecessary. What Photoshop does is it builds a conversion table and to do so, it uses LAB to find the equivalents from source to destination in cases where it needs to translate such color spaces, using 20-bit precision so you get less quantization errors than you would actually converting the pixels to LAB.

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              • #8
                Re: Is Lab color (L*a*b*) still relevant?

                Originally posted by andrewrodney View Post
                Thank goodness. And if Chris Cox had a show, I'd love to see it. I know Chris dating back to before he was a Photoshop engineer and just a kid. Anyone here recall "Chris's Filters"? The work impressed Thomas Knoll and Adobe hired him up just out of school.
                He actually did 2 shows:
                http://www.retouchpro.com/index.php?page=ccrentals
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                • #9
                  Re: Is Lab color (L*a*b*) still relevant?

                  Originally posted by Doug Nelson View Post
                  I think it was Chris Cox in one of my shows, but I'm not going to wade through 6 hours of video to find out, but it was definitely an Adobe engineer that told me that working in Lab was unnecessary effort because Photoshop did everything in Lab behind the scenes anyway.
                  Using LAB as a correction space gives the user access to three color channels not available in RGB or CMYK. Because of this some adjustments are easier when done in LAB. It is not unnecessary effort when you can save time and accomplish more, with better results.
                  Last edited by Shoku; 04-22-2015, 05:39 PM.

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                  • #10
                    Re: Is Lab color (L*a*b*) still relevant?

                    Using RGB as a correction space gives the user access to three color channels not available in Lab, so what?
                    Better results? That's what needs to be proven. Personally I believe you'll get better results, faster, with less data loss using parametric edits from raw data. That's kind of, sort of has three color channels too, and gives the user access to three color channels not available in Lab.

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                    • #11
                      Re: Is Lab color (L*a*b*) still relevant?

                      Originally posted by andrewrodney View Post
                      Using RGB as a correction space gives the user access to three color channels not available in Lab, so what?
                      Better results? That's what needs to be proven. Personally I believe you'll get better results, faster, with less data loss using parametric edits from raw data. That's kind of, sort of has three color channels too, and gives the user access to three color channels not available in Lab.
                      Color selection/separation tools in Lab work much precisely - from my experience - for example you can create better masks in Lab and it is also much faster.

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                      • #12
                        Re: Is Lab color (L*a*b*) still relevant?

                        I think what @Shoku meant to state is that, LAB has two color channels and luminosity channel, this is what gives it its power, working with pure color. There are host of examples as why LAB is powerful, it is really very simple mode to work in if you give it a chance. Just like any other tool, no magic there, you just have to attempt to understand it to appreciate it.

                        - You can easily sharpen an image in the L channel without affecting the the color (over saturation) in the A & B channels. No halos either.

                        - You can manipulate colors without affecting contrast. The opposite is true.

                        - Massive control over color -> B&W conversion

                        - Perform D&B on the L channel without the nasty saturation you would get under RGB, because we are not touching the color in the A&B channels.


                        - Easily and accurately perform color replacement, even those colors you can't touch under RGB (color replacement even affects the tiny and faint specs of color that RGB cant touch, you get real true color replacement since it is done in the A&B channels only, not affecting brightness or contrast, you get very smooth transition).

                        Dog,
                        LAP is not a fad, not workaround, not hard to understand, I do not know why people are intimidated by it, just like any other tool, you have to exert the effort to get to know it and achieve results. The reason we don't see much of it in tutorials is that, people love short cuts. Period.

                        Please search the name Dan Margulis, he is the LAB master.
                        Please watch this 5 minute intro, it will answer all your questions: http://kelbyone.com/course/cs3_lab/

                        Then look up the Man from Mars technique by Dan, here is an example
                        https://www.ledet.com/margulis/Maker..._from_Mars.pdf or here: https://www.youtube.com/watch?v=vS53pAS0RqQ

                        There is video on the Mars subject by Dan himself, try to find it.

                        This one is very useful, it illustrates few things, it also explains what Lab is, I strongly recommend if you watch it: https://www.youtube.com/watch?v=KhfRynutmQM
                        Last edited by Aladdin; 04-23-2015, 12:40 AM.

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                        • #13
                          Re: Is Lab color (L*a*b*) still relevant?

                          Originally posted by Aladdin View Post
                          - You can easily sharpen an image in the L channel without affecting the the color (over saturation) in the A & B channels. No halos either.

                          - You can manipulate colors without affecting contrast. The opposite is true.

                          - Massive control over color -> B&W conversion
                          True in RGB as well if you use the Luminosity blend mode/fade control. And virtually all of the above can be done on raw data, before a true RGB file that could be converted to Lab is even possible.

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                          • #14
                            Re: Is Lab color (L*a*b*) still relevant?

                            That's an interesting thought. Is raw responsible for the decline of Lab usage?
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                            • #15
                              Re: Is Lab color (L*a*b*) still relevant?

                              Originally posted by Doug Nelson View Post
                              That's an interesting thought. Is raw responsible for the decline of Lab usage?
                              Perhaps. The question is, where's the best place to do the work? Good old Dan M. was a master of taking awful rendered images he was supplied and fixing them in Photoshop. He didn't have a clue about photography or raw processing.

                              I know people in these parts are still provided awful rendered images and have to make lemonade out of lemons and Dan's teachings still apply. But speaking for myself, I'm a photographer, only capture raw (outside of the iPhone) and I wouldn’t think of producing the butt ugly images we see in Dan's Lab book (yes I own it). So it depends.

                              It would be useful to know how many non photographers here who retouch are provided a raw file instead of a questionably decent rendered image. Or if they get a poorly rendered image if they could get the raw and start from scratch.

                              It's like getting a good film scan versus a really bad one. Which would you rather start work on? I submit that if given a raw, with a good raw processor, 95% +/- of the Lab work done in PS would be unnecessary, at least for global color and tone work.

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