6.11.2 CIELab Queries

The following equations are useful in describing the CIELab query functions:

CIELab Psychometric Chroma = sqrt(a_star2 + b_star 2 )

CIELab Psychometric Hue = tan-1 ( b_star / a_star )

To obtain the CIE L*a*b* coordinates of maximum Psychometric Chroma for a given Psychometric Hue Angle and CIE metric lightness (L*), use XcmsCIELabQueryMaxC().

To obtain the CIE L*a*b* coordinates of maximum CIE metric lightness (L*) for a given Psychometric Hue Angle and Psychometric Chroma, use XcmsCIELabQueryMaxL().

To obtain the CIE L*a*b* coordinates of maximum Psychometric Chroma for a given Psychometric Hue Angle, use XcmsCIELabQueryMaxLC().

To obtain the CIE L*a*b* coordinates of minimum CIE metric lightness (L*) for a given Psychometric Hue Angle and Psychometric Chroma, use XcmsCIELabQueryMinL().

Next: CIELuv Queries
Christophe Tronche