A convincing texture comprises of three obligatorily channels.
The Diffuse channel gives the general color of the material.
The Bump channel, which gives a relief to material.
Finally the Specular channel or Glossiness to vary the way in which the texture reacts to light.
In the case of the skin texture procedural we quite simply will copy the Diffuse channel into the Bump and Specular.
That makes it possible automatically to reflect the modifications made to Diffuse towards Bump and Specular Level...
When you copy the channel select instance...
Bump + Diffuse.
The dark parts of Diffuse are hollow and the clear ones are bumps.
Specular + Bump + Diffuse.
The dark parts of Diffuse show less light, the clear ones more...
Now the model with procedural texture.
Of course we could make different procedural textures for Bump and Specular Levels but for our needs on this model under development it is a little superfluous...
Another procedural skin texture with a different structure reveals virtual beauty spots.
In the development of the final texture, we can use a mixing of procedural textures and bitmaps. We use Bitmaps for the characteristic details (make-up, lips, scars etc...) and the remainder is the procedural one which takes care of (above of cranium, ear, nose...).