Tiptup said:
Ahh, I misunderstood. All I remembered was a comment about using Lowry's technique to supposedly make Citizen Kane crystal clear. In that case, it wouldn't be the same film anymore, but a simulation of what a clearer version would look like instead.
In the case of Citizen Kane they did screw it up; it was their very first project and I guess they hadn't worked out the software completely, or even what their approach would be. In any case, their Citizen Kane looks very good, but there's almost no grain, its practically video-like. But in the case of movies like the James Bond's or Raiders of the Lost Ark, made much later, they did it as they should. There's the natural film grain, but the dirt is gone. In the case of Star Wars there were some problems, but there was also an aesthetic choice from Lucas I am guessing to make the film look as clean and sharp as possible, so it doesn't look exactly as it normally should in terms of the film quality itself. But its not that far off; its still pretty close to the quality of the original negative. Star Wars should not look like it does in the GOUT, this is the original negatives here and generally there should not be very coarse grain; if you look at the SE of ANH you can see the grain of the emulsion, so nothing's been erased, or at best very little has been minimized.
Dirt removal is good. But, is Lowry's process an actual cleaning/scan that directly interacts with the dirt? Or, is it merely a visual algorithm that compensates for the dirt? In the case of the latter, you'd still have to simulate what the image looked like before that dirt accumulated and it wouldn't be a precise view of what's underneath. (Though, if that's the only option to see the film in way that's closer to its original, clean state, then I'm all for it despite the tiny amounts of information loss.)
Lowry's process is not necessarily dirt per se, but thats what its intended for and what its used for. Basically, dirt looks different than emulsion grain so the computer can differentiate between whats on the emlusion and whats a foreign body on the negative. What it does is look at the frame before and the frame afterwards to reconstruct what the frame between them with the dirt actually looks like and then it erases the speck of dirt and paints in the pixels of what should be there based on the preceeding and following frames. This only works for small pieces of dirt, that sort of speckled dirt that just comes from wear and tear and age; if you have big globs of it or big tears and damage in the film I'm not sure how useful the program would be, so Lowry also has a team of rotoscope artists that hand-paint out the larger dirt/tears/damage, etc.
This process isn't unique to Lowry, I should point out. Their computer program is paricularly effective, but there are a lot of similar programs, and these techniques are pretty much standard now for serious restoration efforts. Criterion, for example, puts their films through a similar but not as aggressive process.