Not with re-shoots or drastic edits. Just by painstakingly looking at each frame of the films and touching up the little things that George Lucas overlooked when he was revising the original trilogy for the 117th time.
Some of them are a matter of simply adjusting the colour balance. Others fix little things, like adding some lights. More significant ones involve overhauling the 5.1 sound mix and even changing the starfields. Or giving Chewie a medal at the end of the movie.
Many of them, though, are just correcting oversights. Dudes falling down when they shouldn't. Laser blasts looking weird. That sort of thing.
To get an idea of the kind of stuff we're talking about here, here's a sample of the changes made just to the opening sequence of A New Hope:
- Restored original klaxon only heard in the original 1977 mono mix.
- Altered C-3PO's line "They'll be no escape for the princess this time" (not in PURIST).
- Re-edited the Imperial breaching scene, partially to remove continuity errors where troops can be seen dying more than once and to eliminate flip shots.
- Removed the full-screen pink flashes when blasters are fired.
- Added lasers to blasters that were fired with no bolt.
- Removed laser that came from the sight of one of the blasters.
- Fixed jump cut after the droids cross the hallway in the middle of the fight.
- Sped up dead Stormtrooper's head that hit the floor as Vader enters.
- Added laser blasts to the hallway behind 3PO as he's looking for R2 so that a trooper doesn't just trip and fall.
The reason we're checking back on it today is that, years after Star Wars Revisited was released free of charge, it's recently been announced that we've nearly got our hands on the sequel, Empire Strikes Back Revisited.
Although originally planned for a late 2012 release, some personal stuff like relocating has slowed down Adywan's progress, meaning ESBR's release has been pushed back to 2013. Since we're already in October, though, that's not too far away!
You can read more about the project at its site, while those who haven't checked it out can download Star Wars: Revisited from fanedit's FTP (though you'll likely need something like thisto get the download working).
Star Wars: Revisited [fanedit]
Star Wars: Revisited [Site]