doublevr
Can upscaling bring higher perceptual quality?
Well this is highly subjective. Upscaling can not bring any more real details, but in can render the available details in a way that is subjectively more pleasing to the eye.
And in fact, your comparison that should prove it does nothing actually shows that upscaling can do a lot.
The edges are a lot better defined, the railings on the ceiling look much better, and the mesh on the ceiling actually seems to have even more details. Whatever upscaling algorithm has been used seems to do a great job in detecting and filling up patterns. Even the pink lights, which look terrible in the original picture look while far from perfect quite a bit better.
It does that at the cost of quite some sharpening halos, so it might be subjective which one is better, especially as most of the improvement seems to happen in the background, while the sharpening halos are most disturbing around the model and the lingerie.
But you certainly can not say it does nothing.
Also WankzVR did some AI upscaling of their old scenes some still shot with 2k and they improved a ton. Especially the actresses look so much better in their upscaled versions, unlike the background which still looks like paintings, which made me wonder if they actually used the photoshootings of the girls they do with their videos to train the NN.
Are the comparable to scenes shot in real with the same pixelcount? Of course not and by a large mile.
But do they look better then the originals? Hell yes.
So you can not say, upscaling never ever can bring anything. The amount and if there even is an improvement varies highly on the algorithms used and scenes, but there are definitely some that show visible improvements, although of course they are no match to scenes already shot with much higher pixelcounts.
You could argue, that it is not upscaling that does the improvement, and you could get the same with the original file and post processing during playback, which of course is true, but with offline upscaling you have basically infinitely more computing power available to do so, so the end result can and in most cases will be better.
