Adding Gamma to the Material Editor

[Maneki]

I think that Daz skins with a Gamma of 3.5 are generally way too dark or go into a greyish skin tone. I tend to always adjust them to lower settings now but there’s no Gamma option in the Material Editor to adjust all at once, yet.

[Alessandro Padovani]

The gamma is used for sss skins to adapt the textures, usually 3.5 works fine enough and you only need to adjust the sss factor, but yes in general the sss skin is expected to be tweaked by the user for best results. This really depends on the daz skin, there’s no way to automate this since sss can’t reproduce volume effects.

We may add a gamma value in the global settings for the sss skin, but more often than not you will find yourself tweaking it depending on the daz skin. I agree adding the option to the material editor may help.

[Thomas Larsson]

Adding gamma to the material editor could be done, but it would amount to a quite significant change. Here is how the color is found: start from the relevant socket, and follow the links backwards until either a multiply node (which sets the color) or a texture node (color is white) is found. Other nodes in that path, e.g. gamma nodes, are ignored.

Have you considered using combo materials instead? Inside the combo node group you can change the nodes however you like.

https://diffeomorphic.blogspot.com/2022/06/combo-materials.html

[Thomas Larsson]

Or perhaps you could change the color to something that is brighter than white. Gamma correction and multiplication by a color are not the same in general, but the skin textures of a given character have pretty much the same color, and then it should be possible to multiply them with something that undoes the gamma correction.

[Maneki]

I can’t really follow, are you talking about the white under “diffuse”? I’m not sure what you mean by “brighter than white”?

[Alessandro Padovani]

Both Cycles and Iray can do colors over 1.0, as rgb = (2.0,2.0,2.0) for example. This can be used as a trick to multiply the texture with a brighter color using the diffuse channel, that’s “base color“ for principled. Another option could be to add a HSV node inside the texture group, then provide tools to edit the texture colors by material set. This was proposed a while back by some user but not implemented, I guess because the actual set of tools for materials is already quite good.

[Thomas Larsson]

Yes, that is what I meant. You can not reach rgb values above 1.0 by dragging sliders, but you can type in arbitrary positive numbers in the color selector, I think.

[Maneki]

This doesn’t solve the multi-editing issue for me since you can’t change the RGB values above 1 in the daz importer UI and the nodes first have to get created by changing the color. I tried increasing the RGB values afterwards to 2 but it looks terrible. Here’s a comparison image where I adjusted gamma, SSS and RGB:

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[Maneki]

Keep in mind that this skin is michael 9 and not supposed to be rather dark looking.

[Alessandro Padovani]

Again, the sss skin is expected to be tweaked by the user, it can’t work as a good automatic conversion. For a good automatic conversion you need bsdf without sss. Then diffuse = 2.0 is only an example, you can of course use other values as 1.5 or anything. Then if you can’t get a tone skin that you like with diffuse and sss, and you absolutely need to tweak the gamma, there’s always the combo materials as Thomas pointed above.

[Maneki]

If there’s no easy solution for adding Gamma to the material editor, it can be closed, I guess.

[Alessandro Padovani]

there's combo materials