Update: Warner Brothers has asked us to remove the images.
Some images have surfaced on Imgur that show some white backdrop, studio images taken for the release of the original Dark Knight. From what I understand, these are images that poster designers would use to craft the extremely popular and highly lucrative (both as a movie advertisement and as individual sale) designs to support the movie. I don't doubt that these would also be used for models, action figures, and as references for computer graphics artists.
The images of Heath Ledger are particularly gripping to me. The photos are good from a technical standpoint, but they are excellent because of the posing. It's obvious that Heath mastered this character, and I understand now more than ever why that mastering eventually led to his death.
I'm pretty certain that one of these images was used for one of the most iconic posters from the movie. Take a look at these side by side:
You can see the whole collection here.