I remember doing a presentation on this topic in college. The research was incredibly hard. This was before Google, so most references I used were found after hours and hours of searching. The presentation was for a Journalism Ethics class and featured examples of altered news photos and discussed the impact they could have on the media.
I was pretty proud of the results. Wish I could find a copy of it somewhere. It’s one of the few things I did in college that I’ve not run across since graduating.