I've had a good deal of experience with CG images and computer manipulated images and this one seems legit. I'm 99% sure it's not been altered in any major way.
That being said, there could be anything inside that dome. Most logical assumption would be some kind of surveillance radar. I would just like to point out that the fact the helo is in army colours doesn't have to mean squat. It could very well be the point, to mask the true purpose of the helo. Actually, if i had to make a guess - i'd put my money on maritime surveillance radar to be used on frigates/destroyers. Could be also used for ground surveillance but helo isn't exactly the best plaform for that, with its flight ceiling limitations.