I've scanned a bunch of old photos and some of them come from those photo albums with the cling film sheets that lay on top of the pics. I couldn't lift the cling film on all of them to get scans of the photos, because that was causing the film itself to break apart, and they weren't my albums to ruin. Getting permission to ruin the albums would have spoiled the surprise that I was scanning the photos for. In any case, I no longer have access to the photos, only the scans I took of them.
So now I have a number of photos like these ones
with filmy layers and a lot of crud on them.
With the better photos that don't have so many problems, I'm just opening them in Gimp, cropping them and adjusting the Levels to counteract the fading since the 70s and 80s when they were taken, but I don't really know how to fix these sorts of problems, or if they're even fixable. What steps would you take in GIMP to edit these photos?
Or, if you'd recommend some other tools, (free or cheap -- I can't afford photoshop) for fixing them, what would you suggest?