"Some of the issues come from these movies being finished for film and projected for film, and that's how people saw them. A lot of things that look a little different on HD or DVD are really the nature of how video treats color space," explains Huebler. A dramatic example of this came up in the 2004 DVD release, with the dimming of the lightsaber cores throughout the trilogy, even to the point where Luke's lightsaber aboard the Millennium Falcon shifted from blue to green in Episode IV.
"We're trying to get back to the intention of the original film experience," says Huebler. "That's really what's going on with the lightsabers. You want that hot white core, and it was just right for film, but on video, that was dampened."
This is complete LFL bull****, by the way. The colors on the 2004 DVDs look the way they do because that's how Lucas wanted them to look.
Perhaps because of the fact that Lucas had lost all of his color-work, he embarked on a new principle--instead of faithfully reproducing the look of the original release and photography, as had been the case on the previous re-release, it could be digitally manipulated to have a slicker look that matched the high-saturation, high-contrast look of the three prequels.
The 2004 SE (it has never been marketed as a Special Edition, though there really is no other label to describe it) had its color correction guided and supervised by George Lucas himself.  Screening the film at Skywalker Ranch, Lucas went through the film with members from ILM, who would be color-timing the digitized film themselves at Lucas' approval. 
This is one of the most controversial aspects of the release. While the revised film obviously is meant to have a deliberate look, what was released is a sloppy mess, in technical terms; blacks are crushed, colors bleed and pop distractingly, video noise is visible because of the oversaturation, skin tones are inconsistent and often very pink, scenes have weird casts to them (i.e. the Millennium Falcon scenes look very green), everything is much too dull and dim, contrast is not nominal, and many of the lightsaber effects are the wrong color (pink for Vader, green for Luke). The coloring is not even consistent with the prequels in some instances, whereas the originals were--for instance, the original blockade runner scene was meant to be Kubrick-esque bright white, while on the 2004 release it is a dull blue, yet strangely in Revenge of the Sith it is the bright white it is supposed to be. Lowry is often mistakenly pointed at as the culprits of these highly noticeable flaws, but in fact it is Lucas himself.
Saving Star Wars: The Special Edition Restoration Process and its Changing Physicality