As someone else said in a much earlier post, PoserPro is more of a side grade then an upgrade.  It essentially has the same features as Poser 7 plus a couple of other items under the hood.  Gamma correction is one of them.  I would suggest that you visit Smith-Micro and read the specs on the program to help you make a decision.  If you follow other threads here at the forum, there are definitely some issues which others have two-cents worth or advice, tips and opinions.  Everything that works in Poser 7 will work in Pro