DreamWorks Shrek2 rendering QA

Hector Yee, who also works for DreamWorks animation, has published at SourceForge, the image comparison component he used for testing Shrek 2 renderer engine.
Perceptual Image Diff (pdiff) - an image comparison utility that compares two images using a perceptual metric.
That is, it uses a computational model of the human visual system to determine if two images are visually different, so minor changes in pixels are ignored.

http://sourceforge.net/projects/pdiff