White, black, and grays have no chroma.
An XcmsFailure return value usually indicates that the given chroma is beyond maximum for the given hue angle.
It returns the maximum chroma along with the actual Hue and Value at which the maximum Chroma was found.
Chroma The degree of saturation of a particular color low chroma The degree of saturation of a particular color low chroma means a pastel color, high chroma means a saturated color.
Robinson, K. & PATTERSON, R.D. APU 3314 The stimulus duration required to identify vowels, their octave, and their pitch chroma.