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 of the better known 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.
even you dont beleved, the lines are patallel. (aunque no lo creas, las lineas son paralelas.)
see the central poin and go back and forward. (mira el punto del centro y muevete hacia delante y hacia atras.)
see the cruz of the center.(mira la cruz del centro.)