I was just comparing some frames from the A New Hope trailer posted on Youtube with the Bluray, and it seems like the color has deteriorated even further, with any remaining yellows drained out of the picture. It may just be the conversion however. There are also some odd details that appear in the trailer that don't appear to be in the blu-ray, despite the lower bitrate of the trailer, and details visible on the Blu-ray that are erased on the trailer. It's very odd, almost like they took another crack at the noise reduction algorithm and sharpening, though I don't know why they would.