Lab Color Model

The CIE LAB color space is a device independent color model that is defined by the CIE. It is based on one channel for Luminance or lightness (L) and two color channels labeled a and b. One problem with the XYZ color system of 1931 is that colorimetric distances between the individual colors do not correspond to perceived color differences. The CIE solved this problem in 1976 with the development of the three-dimensional Lab color space (or CIELAB color space). "L" channel range numerically is from 0-100, "a" channel is on a red/green axis, the "b" channel is on the yellow/blue axis. a and b numbers can either be plus or minus, representing the distance from the center luminance axis, and direction.