that's why it's released on the same day and there's a demo on one of the disks!
it's called marketing!
Here are some quotes from the Star Wars Magazine article entitled The Force Restored, about the DVD transfer process by Lowry Digital Images. There's more about it in the magazine, it's a great read
"There were sandstorms of dirt on the film", says John Lowry, CEO and founder of the Burbank, California-based company. "In the desert scenes alone, we probably removed more than a million pieces of dirt. That means each frame literally had hundreds of pieces of dirt".
"In many ways, the films of the Star Wars Trilogy were victims of their own success. Generally, the more successful a film, the worse condition it's in. When a movie starts out, there are some expectations for what's going to happen with it, how many times prints will need to be made and so forth, then the studio makes a certain number of protection masters for printing. But if they go through them all, they have to go back to the negatives again because the protection masters are just plain worn out. Of course, every time you go back to the originals, you're beating them up again. So, the big movies, the really successful ones, are usually pretty rough".
"The dirt was the biggest single challenge. It was just incredible", he says. "We use automated systems here, which can remove hundreds of pieces of dirt in a scene, but in this case the automated systems just couldn't cope. Last year, Lowry Digital Images performed a digital restoration of the three Indiana Jones films, each of which had about 100,000 pieces of dirt. In the Star Wars films, we removed up to one million pieces of dirt in a single scene".
"Prior to the event of digital technology, colour timing was a hit-or-miss proposition done in a laboratory setting. It was really hard to get right", Blanchard (Lucasfilm Post-Production Supervisor) says. "But in the digital environment, there's a lot more control. You have the ability to fine-tune things exactly the way you want them to be and bring out subtleties in the film you couldn't get by the traditional method of colour timing. On the Star Wars Trilogy, we were able to retime the movie to make it look the way George originally wanted it to be".
Simply put, Lowry says, the Trilogy was the most difficult project his company has ever had. "We've cleaned up more dirt on these three movies than we have on any movie we've ever worked on, including Citizen Kane and that was almost impossible", he says, trying to give some idea of the challenges his technicians faced. The end result.
These films are absolutely stunning.