Watercolor illusion

The watercolor effect is discovered by Baingio Pinna, John S. Werner and Lothar Spillmann 2003 optical illusion, in which the color of contours affects the shape perception of the enclosed figure.

Surrounds you a shape with a double contour of a darker and a lighter color, then the lighter color over a fairly large distance seems to be spreading over the surface of time. If the lighter color on the inner side of the contour, the figure appears sublime, defined fuzzy, and colored. If the lighter color on the outside, so the figure appears deepened sharply contoured and chalk white.