I'm having this issue in premiere where the blacks are brightened when exported. Print screening the image into photoshop, the color of a blank 'black' screen is actually #0c0c0c (gray) when it obviously should be #000000. At first I thought it was due to compression but it happens just the same on an h.264, mpeg and uncompressed avi...
It's also not anything to do with my footage as the same thing happens whether its a black video, picture or solid. Also, everything is fine in the preview window its only after export. I've seen a few topics like this but they had no clear anwsers, I'm thinking maybe it could be a setting in export somewhere that's doing this but I haven't been able to figure it out.
This is in CS5 if it makes any difference and the same is true for After Effects also.