I don't care to know much more detail about the systems used in theaters than I already do, but I can say from experience this weekend your average theater visually appears to be lower quality than a high-definition picture as it is projected. IMAX however is MUCH higher quality and with a screen that is 6 stories high, it LOOKS like you've got a huge high def screen.
I am of the understanding that your images are reproduced on the screen with light and not the result of light projected through film.
Correct me if I am wrong, but whatever the reason those Massive 1 tonne imax projectors do a DAMN fine job.