According to the recently leaked information, Halo 4, unlike the first three first person Halo games released on the Xbox 360 (3, ODST and Reach), will be the first title in the franchise to output full, proper HD visuals at 720p.
Halo 4 will use a redesigned version of the engine that Halo: Reach ran on and will use FXAA to smooth the graphics in the game and give an output of full 720p. According to the Game Informer article that holds this information, the lighting and shading tech have also made “tremendous progress”. It describes one of the opening levels of the game as “”haunted and dim, but still sharp and detailed.”
“An air of reality and natural motion” is also given to the new character models since a new motion capture technology is in place, and it seems to be working much better than before.