Spoilers ahead:
So, I found that in the fifth one, there was a cross shape with "1st" "2nd" "3rd" and "4th" in the quadrants. They had arrows corresponding, and eventually assumed that this meant for the four letter words each picture would stand for, the arrow on the image would correspond to whichever letter to use.
We only had 2 confirmed words, the others being assumed. These were jazz and pawn, where jazz was in the first one, as running it through some things gave us that, and pawn came from number seven, as running it through some filters gave me that. I assumed that the fourth was gray, as no pixel was changed and it was a perfect gray. Somebody said that it might be skin. Number 2 seemed to be a face, and assumed it was a kid as it had to be four letters. Dave didn't have much, somebody thought case as that was what was missing from the full image. Jack didn't have much either, but a key was missing from the full image, but not four letters. Jade was assumed to be fish, as it was overlaid over her. Terezi looked to be coin, as her coin was different