Snippet from an interview with John Knoll in the latest issue of Insider:

When you start a conversion, do you start from the beginning or the middle or the end?

We worked in an odd order, because with Episode I, we were also doing a restoration. One of the first questions that my Associate VFX Supervisor, Dorne Huebler, and I realized, was that if we were going to take this movie and cut it up into 2,000 separate pieces, we had an opportunity to upgrade what those 2,000 separate pieces are. It seemed like we had a perfect opportunity to go back and create a cleaner, sharper, and purer version of the movie.

In fact, the window was closing on that; these archive tapes don't last forever and they haven't been meticulously catalogued and archived because no one thought that was really the master of the film, so it wasn't clear that we were going to be able to find all of them.

Where did you find them?

They were in a variety of places. It was some work to find them and we found about 98 percent of them. So we went back to the original material, and if you look, you're actually seeing about eight percent more movie than in the original release. In the original, there was a bit of cropping, so you lost a little bit of information. We have slightly more of an image now.