OPTICAL ILLUSION
An Eyeglass, My Eye Or A Name?

An optical illusion (also called a visual illusion) is characterized by visually perceived images that differ from objective reality. The information gathered by the eye is processed by the brain to give a percept that does not tally with a physical measurement of the stimulus source. There are three main types of illusion - literal optical illusions that create images that are different from the objects that make them, physiological illusions that are the effects on the eyes and brain of excessive stimulation of a specific type - brightness, tilt, color, movement, and cognitive illusions where the eye and brain make unconscious inferences.

  Circle or Spiral?                                Shading Fades Away 
  Phantom Dots                                    Circle or Spiral 2?
  Freaky Spiral                                     Ambiguous Cube
  Say The Colors                                  Distorted Checkboard