This is an article on malicious photoshopping from nodisinfo.com, and it concerns James Holmes, the Denver theater shooter.
I am not going to get into it specifically but I will say that even though Photoshop did not exist in 1963, that through other means, they were doing malicious photoshopping in 1963. The ridiculous images of James Bookhout with the goofy, wavy eyebrows are a good example. Of course, they made those changes online, but those were yearbooks, which means that there are physical copies of them floating around out there that are unaltered.
The JFK assassination is the most photographically altered event of all time, and by a long shot. I have no doubt about that.