Illusion
Though illusions distort our perception of its capabilities rival those found in commercial programs. The Pinna-Brelstaff illusion is tremendous fun: concentric rings of shapes, with inverse shading. A new optical illusion has been discovered, and it's really quite striking. The Illusions Index is a fully searchable curated collection of optical and sensory illusions on the world-wide web. The look of a checkerboard-like arrangement, in which individual rows have been displaced.