What are HSB and HLS?
HSB and HLS were developed to specify numerical Hue, Saturation and Brightness (or Hue, Lightness and Saturation) in an age when users had to specify colours numerically. The usual formulations of HSB and HLS are flawed with respect to the properties of colour vision. Now that users can choose colours visually, or choose colours related to other media (such as PANTONE), or use perceptually-based systems like L*u*v* and L*a*b*, HSB and HLS should be abandoned. Here are some of problems of HSB and HLS. In colour selection where “lightness” runs from zero to 100, a lightness of 50 should appear to be half as bright as a lightness of 100. But the usual formulations of HSB and HLS make no reference to the linearity or nonlinearity of the underlying RGB, and make no reference to the lightness perception of human vision. The usual formulation of HSB and HLS compute so-called “lightness” or “brightness” as (R+G+B)/3. This computation conflicts badly with the properties of colour vision, as it
