CIELab Color Space
The CIELab color space (sometimes also called Lab color space) was defined by the Commission Internationale de l'Eclairage (CIE) in 1976 and represents a three-dimensional, rectangular coordinate system. The vertical coordinate L specifies the lightness of a color, the 2 horizontal coordinates a and b represent the hue and the saturation on red/green and blue/yellow axes respectively. The CIELab color space is also ideal for representing color differences, since geometric distances in the color space more or less approximate the intuitive color differences. The CIELab color space is standardized as EN ISO 11664-4.