Bright Earth by Philip Ball is a remarkably multidisciplinary book about color. In a chapter about renaissance art, he described the technique of cangiantismo, which is most famously associated with the work of Michangelo. Wikipedia’s entry explains: “Cangiante is characterized by a change in color necessitated by an original color’s darkness or lightness limitation”. The effect is unnatural but it’s what fascinates me most about Michangelo’s paintings.

This article explains how the technique was used in contemporary art such as Monster Inc.