This allows to easily caculate shades of the same color or pick colors
with the same saturation/luminance. In short, all sorts of interesting
things.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit edcbeaf3c941f7a2335fbec47d5248cd9b0e8088)
5858cac873