I know what upscale filtering is.
It's also a system used in PSP games.
Just makes textures smoother and more clear.
Like in the older Project DIVA 2nd and Extend games.
I'm sure it's just the website, thought it could be my browser too.
I went to it, followed what you said, it's pretty basic.
Uploaded an image of the same format. (256x256 .png from Pokemon X & Y)
Clicked "Convert", it opens a new tab, loads for 5 minutes and then brings up a "cannot connect" page.
I'm trying it again and I can get it to work now but I notice no difference in the image.
Trying again...
Okay, it seems I got it to work.
It wasn't working before for whatever reason.
Sorry~