2. Optical Art is a mathematically-theme form of Abstract art, which uses repetition of simple shapes and colors to create vibrating effects, foreground-background confusion, an exaggerated sense of depth, and other visual effects.
3. In the 1960's, the term "Op Art" was coined to describe the work of a growing group of abstract painters. This movement was led by Victor Vasarely and Bridget Riley. Blaze 1964
13. " A bulge" The floor appears to bulge out, though this image consists of only squares.
14. "Primrose's field" This checkered background consists of squares but appears to wave. In addition, this figure also shows a waving motion illusion.
16. "Rollers" Rollers appear to rotate without effort. On the other hand, they appear to rotate in the opposite direction when observers see this image keeping blinking.