Considering that many models are actually trained on L1, L2, “texture loss” or a combination thereof, I am not sure I would say “humans perceive to be realistic

Considering that many models are actually trained on L1, L2, “texture loss” or a combination thereof, I am not sure I would say “humans perceive to be realistic looking”. Then there are some GANs of course doing magic in lieu of coming up with an actual metric that evaluates “human perceived difference”. A more correct view could be “It produces output that was trained on minimizing differences in the pixel/feature-space”. My point being: minimizing actual human perceived differences is seldom/never done but always rather with some proxies or complex loss function constructs that make sure that no scientist has to actually deal with human observers and their preferences ;-)