Joel said:

AntcuFaalb said:

Doesn't the O- have none of the SPFX?

No - you might be thinking of workprints?

http://www.theasc.com/magazine/starwars/articles/sped/ssws/pg1.htm said:

Fortunately, Fox's head of postproduction, Ted Gagliano, made the restoration of Star Wars a personal labor of love, working closely with YCM Labs, Pacific Title, Lucasfilm editorial, ILM and Skywalker Sound. Had the negative been constructed more conventionally, the first order of business would have been to wash it in a sulfur bath a 104F, then wipe it down by hand. But those four different film stocks couldn't be washed together; instead, they had to be separated and washed in batches. That meant dissecting the original Star Wars negative, washing it, and then reassembling it. "That made everybody suck in their breath, " Kennedy says, recalling the stressfull situation. "Thankfully, Robert Hart, the neg cutter on the second and third films, came in to put the negative back together. After doing various tests, we found out right away that nothing beats scanning original negative. Star Wars was an A-B neg cut, which meant that they could actually lift and slug original negative and send it back to ILM whenever we were enhancing a live-action shot. I think this is the first time someone has tried to bring a Seventies effects film back to the big screen."

Sadly, after 17 years, the CRI material had lost so much dye that every shot realized on that reversal stock had to be removed and recomposited from scratch in order to bring Star Wars back to its original glory. Soon, Kennedy had Star Wars Special Edition film editor Tom Christopher (at Skywalker Ranch) and visual effects editor Dave Tanaka (at ILM) searching to come up with the original effects elements so that these shots, as well as other less-than-perfect opticals, could be recomposited digitally.