L * a * b *, also known as CIE-lab, is one of the most common uniform color spaces for measuring object color which proposed by CIE in 1976. It is a color space established to overcome that the equal distance on the YXY color space diagram is not the same color difference we observed.
In this color space, L * indicates light and dark, + indicates higher the numerical value of light and - indicates lower the numerical value of dark; A * indicates red and green, + indicates higher the numerical value of partial red and - indicates lower the numerical value of partial green; B * indicates yellow and blue, + indicates higher the numerical value of yellow and - indicates lower the numerical value of blue.
Beside, thhere is CIE-L *C*H.L * c * h uses the same color space as l * a * b *. It uses cylindrical coordinates instead of rectangular coordinates. L * indicates light and dark, + indicates light and - indicates dark; C * indicates the saturation of the color; H represents the hue angle. The color saturation c * value at the center of the circle is 0. The farther away from the center of the circle, the greater the c *. The hue angle is specified to start from the a-axis and increase in degrees; 0 ° is + a (red), 90 ° is + B (yellow).
L * u * V * color space (also known as CIEluv color space) is one of several uniform color spaces specified in CIE1976 ,
The abscissa represents U * and the ordinate represents V *, which can be used for the detection of lighting sources.