From Bleeding Cool: "Comics Archivist and Publisher Greg Theakston Has Died, Aged 65"
Before digital image manipulation (i.e., Photoshop), the prevailing method of creating images of old comics was "Theakstonization" -- soaking an old comic in a chemical bath that stripped out the colors, and then scanning and retouching the black-and-white line art.
Yes, it's as crude as it sounds Worse, it destroyed both the comics used in the process; I expect you needed one comic for one side of each page and the second for the other side.
I hadn't heard of Greg Theakston before, but I had heard of this color-stripping process. The article mentions that is the 1970s he was one of the organizers of the Detroit Triple Fan Fair. The second year of this early convention was run by Shel Dorf and Jerry Bails. When Dorf moved to San Diego in 1970 he founded the San Diego Comic-con and was its main leader for a number of years.
My first comic-con was the Disneyland Con in 1971. I first attended the San Diego Con in 1972. It was tiny then.