The L∗a∗b∗ color space (also referred to as CIELAB) is presently one of the most popular color space for measuring object color and is widely used in virtually all fields. It is one of the uniform color spaces defined
by CIE in 1976 in order to reduce one of the major problems of the original Yxy color space: that equal distances on the x, y chromaticity diagram did not correspond to equal perceived color differences.
In this color space, L∗ indicates lightness and a∗ and b∗ are the chromaticity coordinates. The a∗ and b∗ indicate color directions:
+ a∗ is the red direction, - a∗ is the green direction
+b∗ is the yellow direction, and -b∗ is the blue direction.