scene referred lut-like solution

Software darktable
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Hi All

I have a practical question about aligning the colors in scene-referred way. I want to create a preset to do different color modifications in one package. Generally I do something like:
• AgX
• color balance rgb (now only the master tab)
• color equalizer
• color calibration
• exposure

Mostly I use color equalizer to tweak colors. However color eq cannot separate well the saturated red + skin tones, or bright sky + dark blue since they are on the same hue.

If I understand well, I have to duplicate some modules and add parametric masks to cover more complex scenarios. If I try to keep it simple and robust to get an all in one solution, I have to go one of this directions:

  • Having multiple color equalizer modules with different luminance parametric masks for shadow, midtones and highlights. (or using the embedded guided filter)
  • Or creating multiple color balance rgb with parametric mask on hue

In both ways I have the questions:

  • How to handle overlapping to create smooth transitions in parametric masks?
  • How to avoid not to change with one modules output the next modules parametric mask input?
  • And overall can it cause some other unexpected behaviour if I do it in this way? Is it common to do it like this?

So to summarise, is there a proper scene referred lut-like solution? I would be happy with LUT 3D module but it seems it’s limited in 0-1 range. Or also something like the old color lookup table module, but on scene referred way.

Do you have any thoughts on this topic or a guide how do to it properly? Or am I on the wrong way :sweat_smile: or missed something what’s already implemented in Darktable? :innocent:

Thank you for all your help!:slight_smile:

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In the manual it says not tested but if you were to place the 3DLUT module after demosaic and before the input profile then it will do a scene-referred transform on the rgb data. You need to match the input profile (colorin) to the expected output profile of the lut for this to work and even then you would likely need to experiment…
(darktable user manual - LUT 3D)

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Thank you for your answer, I read it once earlier but I completely forget this case. Do you know what are the requirements to create such a lut to keep the color calibration module working? Is this the case of technical luts?

I’m mainly searching a styling solution what I can place between color calibration and AgX.