ConvertRGBToYCbCr  531 magick/colorspace.c               ConvertRGBToYCbCr(red,green,blue,&X,&Y,&Z);
ConvertRGBToYCbCr  498 tests/validate.c   ConvertRGBToYCbCr(0.545877*QuantumRange,0.966567*QuantumRange,