Or more specifically, what edits count as being an artist, instead of stuff like photoshopping, cropping, editing text, and others already known that don't let you tag yourself as an artist.

For instance, I know that coloring in images counts as being an artist for tagging purposes, but where does the line get drawn: recoloring images that are already colored, editing colors of a purposely greyscale image, editing to monochromatic colors, or devoiding colors to black and white? What about people fan-animating a series of still images?

Can someone / some people provide an actual list of what counts as being an artist (for tagging purposes), vs just editing an image where you wouldn't count as an artist?

I think (how I see it) the time you tag two artists in one picture is if:

1. artist #1 drew the lineart specifically for artist #2 to color.
2. artist #1 drew the lineart/black & white image did it to be standalone but gave artist #2 permission to color it.
3. artist #1 drew a full colored picture but gave artist #2 permission to animate it.

That's what I can come up with, two artists get tagged when both artists put in relatively equal work into the picture. I don't believe small edits should count. I guess you can take my suggestion as a starting-off point (that I am open to making changes to), but I can't really think of anything else to add to it.

Seconding with @Chameloshi. Minor edits don't count, only when artists put in a noticeable amount of work into it.