In the weekly Bungie update, Luke Smith confirmed that Halo 3 does in fact run at 640p natively, which is then scaled up by the Xbox 360 to every resolution it supports. Luke let everyone know the reason for this lower resolution: the lighting engine. To keep up with a good frame rate and still have their HDR (high dynamic range) lighting system, Bungie had to make the game run in two buffers of 1152×640, a very unconventional resolution.

This ability to display a full range of HDR, combined with our advanced lighting, material and postprocessing engine, gives our scenes, large and small, a compelling, convincing and ultimately “real” feeling, and at a steady and smooth frame rate, which in the end was far more important to us than the ability to display a few extra pixels. Making this decision simpler still is the fact that the 360 scales the “almost-720p” image effortlessly all the way up to 1080p if you so desire.

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Word around the interwebs right now is that Halo 3 only runs at 640p and is scaled by the Xbox 360 to 720p and higher. Beyond3D forum member Quaz51 did some tests to show this.

He tested several edge images in the game using 1:1 mapping on his Samsung 1080p set to come up with his conclusion of 640p. The image above is the edge of a sniper rifle in the game. Quaz51 tested “approximately sixty X360 games (and lot of PS3 games too ), all are 720p except two 1080p (VT3 and NBA street), two 600p (PGR3 and Tomb Raider) and Two 640p (Perfect Dark and Halo3.” He’s very credible over there, so I’m going to believe his results.

So what does this mean? It might explain why some people don’t think the graphics in Halo 3 looks that great. I wonder if Bungie will confront this issue.