Bezold Effect

The Bezold effect is an optical illusion named after the German professor of meteorology Wilhelm von Bezold, who lived from 1837 to 1907 and discovered that a color can appear to change depending on which colors are placed next to it. Bezold noticed the effect while experimenting with ways to modify rug designs by changing only a single color in the pattern. When small areas of color are closely interspersed, an assimilation effect known as the von Bezold spreading effect appears, similar to how spatial color mixing works. When large areas of color are instead placed next to each other, the opposite happens, producing ordinary color contrast rather than assimilation.