Quote - I tried to walk away, I really did. But I can't stand to let statements like this go.

What do you mean white is still white? It most certainly is not. It is now negative grey, a color which appears to be black in preview.

 

Here is the math you did:

 

grey - map

or

.5 - map

Allowing for the moment that your grey is not quite .5, let's just look at the general case.

Black = 0, so when the map is black, you get

.5 - 0 = .5

Areas of the map which are black become grey, or positive displacement. In ZBrush this is supposed to be a negative (inward) displacement.

Grey = .5, so when the map is grey, you get

.5 - .5 = 0

So grey becomes black, or no displacement.

White, which on the map means positive displacement, is a 1.

.5 - 1 = -.5

This is a negative grey, indicating a negative displacement.

Clearly your render shows that all displacement has been flipped. Where the map has black grooves, the object has ridges.

Subtraction, or negation, is the same as forming a negative image, which in displacement terms means reversing everything.

Whether or not you subtract from black, from grey, or from white, doesn't matter. That simply changes the offset of the whole thing.

The correct means to offset the map, where higher numbers should still be higher than lower numbers, is to simply subtract the neutral grey value from the map.

This is correct:

map - .5

Now consider:

white (1) - .5 = .5 (a positive displacement)

grey (.5) - .5 = 0 (no displacement)

black (0) - .5 = -.5 (a negative displacement)

 

0..0

What he said.
because ...I use Zbrush/Poser all the time...and you know you can actually export a 16bit TIFF and use that in Poser now(8 onward...dunno about 7). Just set your zero displacement depth in Zbrush to black. No fuss, no muss:D  Then inside Poser just use "1" displacement for inches or a "0.02" for feet or...such.

Math Node>Subtract: 1(displacement map plugged here)-0.5
This should work if you're using inches as your Poser units and you've exported a "50% gray equals zero depth" map from Zbrush.  

 

http://www.runtimedna.com/forum/showthread.php?63200-SSS-on-Human-Figures/page25
I'm not sure if anyone discussed the displacement/SSS thing...but I know it seems to be an issue with things I'm working on. Could just be that my node setup is lighting the meshes wront. We'll see!