I’ve noticed that the 1997 changes are often the most degraded shots in the film, which is strange because, as they are much more recent than the 1977 film, they should be in better shape. But more often than not I’m having to repair the color. I guess these additions were even more shoddily preserved than the original elements.
The 2004 master is a 2k scan that has then been denoised with a bunch of DNR and then regrained to hide that fact. For the original negative and stuff recomposited in 2004, this is the only stage of detail loss. But for all the shots composited in 1997, it’s:
film, to a 2k scan, add CGI (possibly denoise based on the shot), print back to film, to another 2k scan, aggressive denoise, regrain.
The '97 stuff suffers more generational loss due to Lowery’s process.