3 ms·

What is the goal of your hue shift? If your goal is to otherwise preserve color relationships, then you should use a perceptually relevant color space. But ma

What is the goal of your hue shift? If your goal is to otherwise preserve color relationships, then you should use a perceptually relevant color space. But maybe you have some different goal...?

mark-r 6y ago
Sometimes the goal is just to change the color of an object while retaining the shadows, highlights, and textures. Suppose you had a picture of a blue car and wanted to know what it would look like in yellow.
- jacobolus 6y ago
  Personally I use this tool I built as a Photoshop action over a decade ago, https://www.hcs.harvard.edu/~jrus/colortheory/jl.html https://www.hcs.harvard.edu/~jrus/colortheory/jl.html (see the animation at the bottom showing almost precisely what you are asking about) Initial discussion: https://www.ledet.com/margulis/2010HTM/ACT08-Jacobs_Ladder.htm https://www.ledet.com/margulis/2010HTM/ACT08-Jacobs_Ladder.h... An HSV hue shift (or whatever similar thing you are thinking of) yields horrible results in this use case.
  - mark-r 6y ago
    That example looks like it's working directly with RGB, which I expect to be correct. I've also seen it work well in HLS. But I worked on a tool where we were told to change from HLS to CIELab because it would be better, and it turned out to be much worse in practice.
    - jacobolus 6y ago
      I almost always use CIELAB as a working color space for photographic work (my action linked previously converts to 16 bit/channel CIELAB space as its first step, though you could use a similar type of tool in RGB mode if you wanted to). But I have a pretty good idea of the final RGB (or other) gamut I am aiming for. Photoshop is definitely designed RGB-first, and some of the tools get a bit clunky in CIELAB mode. It is still an improvement for most of what I want to do. I have many ideas for better image color manipulation tools.

3 ms·

What is the goal of your hue shift? If your goal is to otherwise preserve color relationships, then you should use a perceptually relevant color space. But ma

by jacobolus 6y ago

What is the goal of your hue shift? If your goal is to otherwise preserve color relationships, then you should use a perceptually relevant color space. But maybe you have some different goal...?

mark-r 6y ago
Sometimes the goal is just to change the color of an object while retaining the shadows, highlights, and textures. Suppose you had a picture of a blue car and wanted to know what it would look like in yellow.
- jacobolus 6y ago
  Personally I use this tool I built as a Photoshop action over a decade ago, https://www.hcs.harvard.edu/~jrus/colortheory/jl.html https://www.hcs.harvard.edu/~jrus/colortheory/jl.html (see the animation at the bottom showing almost precisely what you are asking about) Initial discussion: https://www.ledet.com/margulis/2010HTM/ACT08-Jacobs_Ladder.htm https://www.ledet.com/margulis/2010HTM/ACT08-Jacobs_Ladder.h... An HSV hue shift (or whatever similar thing you are thinking of) yields horrible results in this use case.
  - mark-r 6y ago
    That example looks like it's working directly with RGB, which I expect to be correct. I've also seen it work well in HLS. But I worked on a tool where we were told to change from HLS to CIELab because it would be better, and it turned out to be much worse in practice.
    - jacobolus 6y ago
      I almost always use CIELAB as a working color space for photographic work (my action linked previously converts to 16 bit/channel CIELAB space as its first step, though you could use a similar type of tool in RGB mode if you wanted to). But I have a pretty good idea of the final RGB (or other) gamut I am aiming for. Photoshop is definitely designed RGB-first, and some of the tools get a bit clunky in CIELAB mode. It is still an improvement for most of what I want to do. I have many ideas for better image color manipulation tools.