However, image is not a wave. Sampling theorem applies beautifully to audio, but only to a limited degree to images. Some filters make sense in frequency domain

However, image is not a wave. Sampling theorem applies beautifully to audio, but only to a limited degree to images. Some filters make sense in frequency domain, eyes are sensitive to certain frequencies more than others, but it all breaks down on hard edges, which don't behave like square waves. The problem is that in images the Gibb's effect is visible and annoying (ringing artifact). If sampling theorem applied, people wouldn't be able to see it, like they can't hear the difference between square waves shifted by a half of a sample.