Phredreeke, on 03 March 2021 - 08:25 AM, said:
And emulating the look of the original image, with deficiencies, is the whole point of my dedither and repalettisation scripts.
I may be wrong but personally I think that with the upscale, the deficiencies become a whole new kind of bad, because the low-res original at least had the excuse of being low-res and produced back in the early-mid 90s.
Basically what you're doing is depixelising the original image, not bringing it up to a new resolution. Look at the outline of the back of the left hand in the original image. It's all jittery with little to no anti-aliasing, and your upscale happily reproduced that. In the animation you posted, there's a notable artifact near the knuckles, pixels go back and forth in a shape that would not be there if the same two-frame animation were produced from a higher-resolution digital image.
BTW, here's an idea that seems worth trying which I keep forgetting to tell you about: take a high-res 8-bit texture or sprite, try to scale it down to a resolution more comparable to stock
Duke3D textures (64x64,128x128), and then upscale it as if it were an originally low-res image with your method, then compare the result to ground truth. Earlier you mentioned a certain "unresize" model which I gather makes a downscaled image more like as if it were originally created at that resolution? If yes, this would much simplify the task of making a low-res texture from a higher-res one.