All this time I thought the blue colour-cast to the Tantive corridors was due to poor quality control. But no, evidently, George Lucas aimed for the colder, bluish tone!
http://www.dvdscan.com/sw_comp_2.htm
And the crushing of the blacks and loss of shadow detail? Lucas apparently wanted to "emphasize the mood and the things about to happen".
http://www.dvdscan.com/sw_comp_3.htm
Full article is here if anyone wants to read it (I'm too lazy). I'm sure there are more amazing revelations in there somewhere. Post to this thread if you find any.
(I just remembered reading somewhere the explanation of Luke's green-coloured lightsabre aboard the Falcon. Apparently, the lightsabre is set to "training mode" - presumably to stop him from accidently slicing off parts of his own anatomy during his practice sessions.)