Looks nice, is this xBRZ or SuperxBR?
No. To get the final output I had to use a combination of filters, each one with its specific strength. The original assets from the psx game is a bit noisy (jpeg artifacts and small details that behave like noise in high res).
The process needs three passes:
First Pass: I have used
waifu2x to scale by 2x, because it has a very powerful technique of noise reduction, besides its unmatched capacity to thin edge lines (this is necessary to not blow up edges at higher resolutions).
Second Pass: the great capacity to thin lines from waifu2x is its weakness too in a second pass (I tested it and the results aren't good), so I didn't use it here. A better filter for a clean source is
Super-xBR, which I used here to scale from 2x to 4x size. It's the only one to not introduce aliasing, while keeping sharpness high. I didn't use it at first pass because it doesn't scale noise well.
Third Pass: To finalize, I need a linear filter to scale the 4x output from the earlier passes to the desired final resolution. There are many linear filters available (bilinear, bicubic, lanczos, jinc, etc) and the best one is
Jinc, because it keeps sharpness high and introduce very little aliasing. So I've used
Jinc here.
EDIT: Just found a second method to get similar quality using only waifu2x.
First Pass:
waifu2x using Photo Model and Highest noise reduction. The highest set is necessary, because there are too much noise, mainly in dark areas.
Second Pass:
waifu2x using Photo Model and None noise reduction (the first pass is enough for noises).
Some more screenshots:
