Sounds like a really neat coffee table book that came out a while ago. Pictures, first clothed then unclothed of adult film stars in the same poses. There was actually a documentary on the making of that book - the photographer used a really old film camera for the photo shoots, one that stood in a big box and the "viewfinder" pic was actually still upside down.

I'm completely blanking on the name of the book, (I'd hoped typing out the description would tickle the memory free) and it just doesn't seem like the sort of google search one should do from work. :-)