Hunter Lab

It is another colour space that is referred to as Lab, like CIELAB ($L^{\ast }{a}^{\ast }{b}^{\ast }$). It was also derived from CIE 1931 XYZ Colour Space.

L is a correlate of lightness and is computed from the Y Tristimulus value using Priest’s approximation to Munsell value: $L=100\sqrt{\frac{Y}{Y_n}}$, $Y_n$ is the Y tristimulus value of a specified white object. a and b are termed opponent colour axes.

CIELAB has almost entirely replaced Hunter Lab.