I asked this in a thread about displacement maps for H3. 

So we can use displacement maps to make veins on skin, but how can they be colored to look like the greenish blue veins beneath human skin?

A blue /green diffuse -blender node using the displacement map as a mask?

Someone suggested that.  Here's the screenshot of their suggesting.  When I tried it, it turned the skin blue.

It would have helped if you had the displacement expanded so that we could see it.

I'll guess that the veins are light grey on a darker grey background.  You need a black background.  Try running the displacement map to a math function node (subtract) and subtract 0.5 or whatever it takes to just reach a black background.  Run this output to another math node to take the square root to restore some dynamic range.  Run that output to the root shader node's displacement input.

It wasn't my image, it was from the person who suggested it.

"You need a black background.  Try running the displacement map to a math function node (subtract) and subtract 0.5 or whatever it takes to just reach a black background.  Run this output to another math node to take the square root to restore some dynamic range.  Run that output to the root shader node's displacement input."

I think that's what the M4 displacement maps do, so I will try copying their nodes.

Quote - It would have helped if you had the displacement expanded so that we could see it.

I'll guess that the veins are light grey on a darker grey background.  You need a black background.  Try running the displacement map to a math function node (subtract) and subtract 0.5 or whatever it takes to just reach a black background.  Run this output to another math node to take the square root to restore some dynamic range.  Run that output to the root shader node's displacement input.

That's right, I posted that Screen Capture, and my displacement  is black Background with veins in white and shades of gray, that's how the displacement map must be to work this way, and the veins map must be plugged to the displacement channel not the bump

Ok, here is a node function which will get you the de-oxegenated looking veins with displacement, using TrekkieGrrrl's map.

To what is image map 4, the top right, attached? 

Image map 4 is TrekkieGrrrl's vein bump/dsplc map.  Its output -the purple "cable"-  plugs into the upper socket of the math node in the bottom right corner.

     The math nodes process it and hand it off from right to left, ending with an image that has grey veins on a black background.  The last math node (bottom left) then plugs into the displacement socket and also controls the amount of blending.

• "math functions"     darkens the entire image until the background is black, with only the veins, etc remaining.
•   "mat functions 3"     is a clamp;  any pixels which are less than zero (i.e., negative) are set to zero.  I don't want any negative pixels when I take the square root.
•   "math functions 2" brightens the veins by taking the square root.  The square root of a positive number less than 1 is always greater, though still less than 1.  For example, the square root of one half is 0.7071...

That does a nice job.  To get the veins to pop out, connect that top right image map (the displ map) to bump.

Thanks for all the help.

seachnasigh,

I confer the title of Node Elf upon you.

Quote - seachnasigh,

I confer the title of Node Elf upon you.

Gratefully received, BB!  :biggrin:

Mr bagginsbill reg. veins in your first vss prop you had a "spots node", you could could change the spots to a veins map, change the color and use the proper dispacement, I think it would produce a
good effect. Ive been trying to get a veins node, but I'am not very good with material room.