A note on illusions.
The crucial factor in illusion is not in perception but rather in the assumption that all two-dimensional drawings represent two-dimensional reality. This leads in some cases to making unwarranted comparisons between parts of the figures.
D003118:Color Perception; D003867:Depth Perception; D006801:Humans; D007088:Illusions; D007257:Information Theory; D009903:Optical Illusions