Take a look at the individual segments zoomed in: https://i.imgur.com/H4y4XTH.png https://i.imgur.com/H4y4XTH.png I think what's happening is the brain is proc

Take a look at the individual segments zoomed in: https://i.imgur.com/H4y4XTH.png https://i.imgur.com/H4y4XTH.png I think what's happening is the brain is processing the separate color segments individually, instead of a continuous line. And at an individual segment level, it's much harder to detect a curve on the bottom pieces than the top. Notice the red line I drew. The bottom pieces fit much closer to a true line than the top pieces.