@dave
It's pretty old at this point. AI upscaler trained for anime art. It does a good job, but I'm autistic about such things, because it just isn't the original image, in it's pure form. It's like adding an Instagram filter to Mona Lisa and pretending it's better.
@alyx @dave i use waifu2x sometimes because it's easy and can help things look better when used sparingly. it's really only if i NEED something in a higher res, though, and don't care if there are any weird squiggles in it.