Creating new skin textures from scratch

his.royal.duckness

I've found a lot of great resources on how to customize Genesis characters, create morphs, add geoshells, etc, but they all generally start with a pre-existing skin texture that just gets "tweaked" with some minor touchups. I haven't found very many comprehensive tutorials at all on how to create a base skin from scratch. There was a quick and dirty video that Jay did on how to paint a picture over an existing skin texture using a stencil in Blender, but it was kind of more a Proof of Concept tutorial than an actual start-to-finish. There's quite a few different tutorials for sale in the Daz store, but they kind of gloss over exactly what they cover in terms of texture creation and I don't want to spend $50-100 a pop just to find out they teach how to customize an already existing texture or the info is so old that it's practically irrelevant now. 

So I'm wondering if anyone can recommend a good tutorial that explains how to create from scratch or take an existing model's skin and completely paint over it with some HQ photos, do any necessary blending or touch ups and make it look like a production-worthy model? I don't care what software is used as long as it's something easy to follow. 

Thanks!

cgidesign

Example for a google search:

"how to make a skin texture for 3d"

Example search result:

This video by J. Hill explains one concept to do this (painting texture on top of a high detail normal map).

This second video explains how to make the high detail normal map.

I don't care what software is used as long as it's something easy to follow.

Those videos cover a complex topic, so they are not "easy" per se but quite good to get an understanding of the concepts.

There is another concept where you don't create the normal map (and / or displacement, bump etc. map) by yourself but instead use scanned data (somebody else has scanned human skin and provides those maps as ready made textures).

Example google search for this concept:

"how to make a skin texture with scanned data"