L*a*b* Color Value
A color expressed in the L*a*b* color space is composed of L, a, and b component values. The L color component is expressed as a numeric value within the range of 0 to 65280, which maps to 0 to 100 inclusive. The a and b components range from 0 to 65535, which maps to -128 to 127.996 inclusive. The color value is defined by the CMLabColor type definition.
struct CMLabColor {
unsigned shortL;/* L component of color in Lab color space */
unsigned shorta;/* a component of color in Lab color space */
unsigned shortb;/* b component of color in Lab color space */
};