Gamma correction is a separate topic which, as I mentioned in my post, applies to all Poser versions (including P8) with material room capacity.  PoserPro has it built in and so will PoserPro 2010 when it becomes available.  Search for gamma correction and bagginsbill.  Bantha has also created a Wacro script to automatically insert Gc nodes in the material room.  A time saver.  Do look over bagginsbill VSSProp for skin texture enhancement.  It has Gc already builtin and will make a tremendous improvement in your renders.