This example is most likely completely legal, I will be the first to say. Ethically, however, I feel that it is one of the worst offenders because of the context.
When someone takes photographs, chops them up and “Frankensteins” the chunks together, that is basic photo manipulation and is a completely acceptable method of design unless you are using copyrighted photos. I’ve touched on this elsewhere on the blog, but the basic rule of thumb is to always change it far beyond what the source is if the works are copyrighted.
In my personal opinion, though, I feel that any time you cut and paste from an ARTIST, you have moved into the realm of unethical no matter how much you try to hide it.
The reason for this is because the source artist spends their entire life learning how to draw/paint/etc in order to create an original piece of artwork. When another artist takes that artist’s brush strokes and cuts and pastes them into their own digital file in order to pass it off as their own work, I feel that is the definition of lying. There is a level of deception with all plagiarism, of course, but this is even worse because you are collecting a check from someone who is paying you to create something original. If all it takes to be a professional artist is to go around cutting and pasting from masters, then why is anyone even trying to create original art? It isn’t hard to see how this hurts the industry at large.
The image above is changed a lot, but it is clear as day that the Joker image on the left was split down the middle, flipped in order to be symmetrical, and then painted over to take out details. While it won’t even stand up to the “red outline test”, you can see that the teeth have the same glimmers (again, keep in mind it was split and flipped) so this is not a case of simply being “referenced” or “copied”.
What makes this even worse is that Alex Ross is a living artist who survives on his art.