The area lite by the light beams seems to be highly saturated by the blue glow, it could account from some of the awkward changes in the mountains around that area. I can see it really isnt flowing that well to the left, like rundown mentioned but the heavy saturation of color and poor visual quality might account for this but its still up in the air.
What it looks like to me is a rendering issue because we see a green area inside the blue zone, something i would expect from an early version of an unfinished game, not a photo-shopper with even a little talent.
All the objects and ground/landscapes are picking up a slight blue hue or reflection from the white beams emitting the blue glow. Again it can be faked very easily, but they did a decent job on it and in some of the fakes i see it isn't nearly as smooth.
If i didn't know any better i would say it looks like the image is being played on a 3D mode but because its a photo of a screen its impossible to tell for sure.
I can see a protecting film laid on the screen in the top left corner so we can be sure its a real photo of some TV screen. Or if its photoshopped than the guy was smart enough to add that for the very few who would see it and care, either that or he took a picture of his computer monitor.
The halo 4 logo is beyond easy to replicate and can be found on the net. If I didn't see it there i wouldn't even know if it was supposed to be Halo, and is something a faker would put on immediately. whether or not 343 would place it there is unkown and it can't do anything to prove the picture.
The weapon feels like something from CoD, but the ammo counter is distinctly a Halo style piece. i just can't be sure without more info.
I feel it might be legit for a photo, but it may not be Halo itself. Someone could easily put the logo there and change the ammo counter color, or take a picture of Skyrim, add blue lighting and white beams and put a rifle there and say "OMG ITS HALO 4!!!"
Best way to find out is to find out where that gun came from, that will give use the proof to be sure what it is we are looking at.
