Here's a radical idea for you. Keep the transmap image, but get rid of the color texture image and replace it with a 100% procedural approach.

I wouldn't have tried this without matmatic as it requires a lot of math nodes.

This is a quick test as proof of concept. I did not put in all the math to produce all the features required in the color map. In particular there is a section on the lower right that has to swap the U/V coordinates to make the hair strands go horizontal instead of vertical. And within THAT, there is a tiny strip where they go vertical anyway. Also the darkening at the roots was only partially implemented for the upper row of color strips. The lower row still needs that treatment, and the upper row of strips should not all be darkened at the top. But all of that is fixable.

I used a carefully tuned Fractal_Sum node to generate the hair strands. The basic premise seems sound to me. In addition to dealing with all those coordinate issues, I'd probably add another layer or two of hair strands that are slightly out of alignment with the bottom layer.

Once I get all the math worked out, you simply would have to edit two color parameters to get any look you wanted. I could also add some distortion to the strand generator to get wavy hair.

What do we think?

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)