Horizon Forbidden West "Average Skin-Tone" Extraction & LUT Workflow

german01

I recently came across a presentation slide regarding Guerrilla Games' character texturing pipeline (specifically the improvements made for Horizon Forbidden West).

I would be interested in finding out how they extract the average-skin tone leaving only the skin variation, and if they use any other maps, such as hemoglobin and melanin.

And then how to generate the LookUp Table and its use.

They don't go into much detail on this topic. I would like to be able to replicate a system similar to theirs, but I can't find much information about it.
Any tips on how to achieve this or information that has been published elsewhere would be greatly appreciated.

Thank you very much in advance.

https://youtu.be/JmC-OQYp7zE?t=2959

Noren

No idea how they do it, but in photoshop and similar, you can pick the average skin tone of your original map, invert that, and apply it with linear light at 50% opacity. Then apply your skin tones with linear light and 50% opacity as well (maybe some additional tweaks for really dark skin). If you do it yourself with shaders, there is probably some more straight forward math.

With melanin, you mean a mask for e.g. the inside of the hands?

Edit: scratch that, there seems to be a problem with clipping and possibly gamma when doing it this way

poopipe

Extracting aerage skin tone is likely just blur since that averages the values