Never one to miss an opportunity to ogle Emma Watson's chest with impunity, I decided to do a little "forensic investigating" to see if there is any explanation that's a bit less sleazy. After many cries of "enhance!" were heard inside my office, I suddenly realized what happened.
See, I was having trouble getting the purportedly "before and after" images to line up properly. Things seemed skewed, shadows didn't seem to fall properly. Then I noticed the young bloke on the right's tie, and how it seemed to be at a completely different angle in the two shots.
"It's almost as if this shot was taken with two cameras at the same time," I said to myself. "Why on earth would they do that??" Then I noticed the overlayed text on the "after" image, and how it proclaimed that some of the movie would in fact be projected in 3-D iin the IMAX theaters.
Eureka! Knowing that 3-D movies are made by filming them with two cameras strategically placed a small distance apart, everything suddenly made sense.
What they're calling the "after" image is actually the shot captured by the camera that was closest to Emma, giving it a view to more of the "profile" of Emma's boob. The "before" image is the camera further away with a more "head-on" shot, making it look flatter.
Here it is as a 3-D anaglyph (that I just generated in The Gimp):
Hopefully you have some 3-D glasses around (mine say Spy-Kids 3D on them) to view this with, but I assure you that I've gotten to the bottom of it. There's no conspiracy here. No one is trying to enhance Emma (nor would the be able to if they tried; she is already a textbook example of perfection as-is), the poster designers just didn't realize that when they 2-D-ified the 3-D promotional poster (I haven't seen said poster, but I am deducing its existence based on my research), the old one used the "left" frame, and the new one used the "right" frame.
I'm sure that no one even thought of this, not realizing that two frames captured mere inches apart would cause any problems. Sadly, with thousands of internet fanboys nitpicking, it can make a huge difference.
Anyway, spread the word. No one is trying to pull anything, it's just an oversight.
Oh, and if you've seen the 3-D poster I'm postulating the existence of, I'd sure like to hear about it.
UPDATE: Some people don't quite understand, so I quickly drew up this top-view approximation of what's going on. It is not to scale.
Does that make more sense?
UPDATE: Apparently not... I thought the 3-D anaglyph would be self-explanatory, but sadly nobody actually owns the glasses required to see it. So I tried to draw a simple drawing explaining it, but that didn't do it either. See, in the drawing, the red/blue lines are meant to show what your eyes are doing when looking at a 3-D scene -- not the cameras. 3-D is all just trickery designed to fool our brains into seeing flat images the way we see objects in the real world. In the real world, each eye sees things from a slightly different perspective, and our brains calculate differences in those perspectives to tell us how far apart things are, how round, etc.
With a 3-D anaglyph, an entire scene is presented encoded in colors so that the special glasses can "filter" the view such that each eye is seeing a completely different view. But the magic really happens when the eyes start to focus at different parts of the picture. The brain is usually fairly convinced that what it's seeing is an actual scene, so your eyes begin to move about the image as they would in a normal everyday view of the world. If a 3-D image is made properly, you can focus your eyes on one element of the composition, then move to one "deeper" into the image, or "farther away" from the camera, never breaking your brain's sense of 3-D.
The 3-D anaglyph above is simply just the "before" image set as the left eye's view, and the "after" image set as the right. Nothing else was done to them, yet the 3-D encoding is perfectly realized when you put on the glasses. This doesn't happen on accident folks. My drawing above was demonstrating what your eyes would do if you'd look over at Emma's side of the composition in such a 3-D scene, to show that the closer eye would see her breast with more of a profile, and the further away one would be more head-on, thus explaining the difference in the curve of her breast and stomach. And if your eyes would behave that way, so would the two cameras.
I decided that perhaps a better explanation would be to try to take 2 similar shots myself. Now, I didn't take these at the same time, and I had to just sort of estimate the exact amount to shift the camera, so it isn't perfect -- but I think you'll get the idea. The subject of the photo was not altered in any way, the only differece between the two shots is shifting the camera about 2" laterally between taking them.
Obviously the effect is more pronounced due to the much smaller scale and the inaccurate camera movement, but I think this really concretes what I'm saying. If I had more scale action figures to play with -- and a lot more time -- I could set up the entire shot, but that's way more work than I'm prepared to put in.