This is a rather basic illusion created by setting each of the colour channels to a slightly different grid pattern (more complex than just that).
- Red channel is a 14x16 cell grid
- Green channel is a 15x15 cell grid
- Blue channel is a 16x14 cell grid

This overall creates a rather interesting illusion that appears to stretch and squeeze whenever you move your head backwards and forwards, and produces some other interesting effects when scrolling.