extrapolation
The human eye has an amazing ability to extrapolate, linking bits of images when the total view is obscured by an irregular obstacle. It is as though the eye can "see" through the obstacle and perceive the full image. Hans Drevermann has sketched a snake hidden by parts of a black detector (bottom). Paint the detector in the background colour (top), and the snake is difficult to recognize. If the eye can discern intervening obstacles, a partially hidden object can still be perceived.