EDIT: misunderstood, thought it was referring to original article not grandparent. <strike> No. HSV and HSL are two very similar physically-based color models

EDIT: misunderstood, thought it was referring to original article not grandparent. <strike> No. HSV and HSL are two very similar physically-based color models that only loosely map to perceived brightness and perceived grayness: https://en.wikipedia.org/wiki/HSL_and_HSV https://en.wikipedia.org/wiki/HSL_and_HSV They are nice cylindrical shapes because they are straightforward transformations of the RGB cube-shaped color space. By contrast, HCL is a biologically-based close approximation of actual perceived brightness and perceived grayness: https://en.wikipedia.org/wiki/Lab_color_space https://en.wikipedia.org/wiki/Lab_color_space It has a funky shape because the frequency responses of the color-sensitive pigments in the cones of our eyes are complicated: https://en.wikipedia.org/wiki/CIE_1931_color_space#Color_matching_functions https://en.wikipedia.org/wiki/CIE_1931_color_space#Color_mat... </strike>