D3 support for CIE L*a*b* and HCL. These perceptually-motivated color spaces are designed with humans (rather than computers) in mind. RGB and HSL interpolation can cause unintentional grouping due to parts of the color space appearing more visually similar; L*a*b* and HCL, in contrast, are perceptually uniform. For more information, see Gregor Aisch’s post How To Avoid Equidistant HSV Colors and Drew Skau’s post Dear NASA: No More Rainbow Color Scales, Please.
You can create L*a*b* or HCL colors directly using d3.lab or d3.hcl. For example:
var steelblue = d3.lab(52, -4, -32);
var steelblue = d3.hcl(-97, 32, 52);You can also convert from RGB or HSL. This is useful for creating brighter or darker colors with uniform changes in perception: