I got my Clerks II movie poster in the mail and the first thing I thought of was this thread. A non-Beyonce example of the same phenomenon:
Rosario Dawson at the movie premiere:
Rosario Dawson on the movie poster:
I noticed that she "changed colors" in the movie, too. It seemed she was more tan when she was the nerdy boss and, as she shifted to love interest," she seemed to get lighter (as well as several other changes to her appearance but that's another story).