You could make it difficult to get to by writing your own software to decrypt/view an encrypted set of pictures. You would then include the software and encrypted pictures on a disk. That would not stop it from being copied, but it would make it more difficult.
well you could write your own viewer that uses a proprietary image container (instead of jpg, bmp and sorts), but then you would have to find a way to tie in print screen so when it was pressed it changed the picture to a black rectangle