It would probably make a lot more sense to just do all of the color schemes as indirect lookups on a “swatch” texture. The math is a lot simpler, it would allow other things like baking gradients in easily, and would also give a lot more flexibility when it comes to various interactions; for example, I’d be able to encode arbitrarily many skin colors into things, which would allow for argyle and such as well. Plus it would give me even more color slots to work with, so I could also have separate colors for the lips, tongue, nose, and inside of the mouth (which are currently stuck using the same color).
Also, doing that would only require two of the channels in the pigment map, which would free up the other two channels for the occlusion and subsurface maps, which would make everything way more efficient overall.
Yeah, I like this idea.