Quote - I'd just like to add in here that ClawShrimp is correct. The best way is to paint it as a separate map, to be honest. These other methods work but not always and not always well.

 

very true..simply desaturating or inverting a color map wont create a decent bump map.that's a method to avoid if your looking for fine bump mapping

another link:
http://forums.cgsociety.org/showthread.php?f=46&t=339508&highlight=skin

Angelouscuitrys comment:

* "Now you have a Perfect Grey.  If you were to fill the top layer of your texture map with it, and then plug that image into your Poser Material Room Bump or Dissplacement nodes, this Bump Map would do absolutely nothing..."

applying a gray shade to displacement will have an effect,if you want no effect then use black,most 3d apps use gray(128,128,128) as the base level,meaning it has no effect,but Poser treats black as the base level,this can easily be changed via nodes but by default black is the shade that has no effect on displacement

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