Comment by fredophile

I'll admit that I skimmed the article but I have the feeling this CNN didn't learn what they intended it to learn. Looking at the examples shown they started with a full resolution image and applied some downsampling algorithm to get the lower resolution to apply their algorithm to. Their algorithm has learned to undo the downsampling that they applied. This doesn't mean it will perform well on images that haven't been downsampled or images that have been downsampled in a different way.