Basically it looks as if they darkened the scene considerably (perhaps with the aim of making the "Emperor's slugs" less noticable, though I've also heard that Lowry Digital used a kind of automated color timing system, which at least explains why the saber colors are so off, but possibly the contrast thing too).
So if you crank up your brightness/contrast, it makes the scene look much better, more how we all remember it being in the 1997 SE's and the original. Darken it up though, and you'll see the weirdness.
Basically when I was showing my DVD's to my sister and her boyfriend, we noticed that if you turn up the brightness to fix the sabers in ROTJ, it's TOO BRIGHT for ANH, because you can see the matte boxes around the fighters. Darken it up to hide the matte boxes in ANH, then in ROTJ it's too dark and the sabers look off. So tune your set up before viewing I guess. PowerDVD lets me set custom brightness/color settings for profiles, which saves time.
Too bad about some of the matte boxes in ROTJ though, that are blue or green... they can't be hidden! :P