Op Art

Op art, also known as optical art, is a style of visual art that makes use of optical illusions.

Optical art is a method of painting concerning the interaction between illusion and picture plane, between understanding and seeing. Op art works are abstract, with many pieces made in only black and white. 

When the viewer looks at them, the impression is given of movement, hidden images, flashing and vibration, patterns, or alternatively, of swelling or warping.

Some op art artists are: Josef Albers, Richard Allen, Getulio Alviani, Richard Anuszkiewicz, Tony DeLap, etc

Bridget Riley: 'Movement in squares' (1961)

Richard Anuszkiewicz: 'Intrinsic Harmony' (1965)

Author: Wikipedia (copied by Jaime Torner Amigo)