A HSV color picker.

Example of hue distortion for deep blue colors. Notice the purple shift as saturation decreases.

Example of hue distortion for deep blue colors.

Example of colors HSL considers to have the same lightness.

Example of hue distortion for blue colors. The distortion in HSLuv is different from that in sRGB and is caused by the Abney effect.

Example of constant lightness in HSLuv, with low “saturation” close to the center of the circle and maximum “saturation” at the edge. Notice how the blue and red hues are much more saturated than surrounding colors.

Slice of colors with constant “saturation” in HSLuv. The scaling to match the uneven shape of the sRGB gamut makes the perceived chroma vary unevenly.

A slice of the gamut with a constant blue hue.

A slice of the gamut with a constant yellow hue.

Example of constant “lightness” in Okhsl.

Slice of colors with constant “saturation” in Okhsl. While not matching perceived chroma fully it is smoothly varying.

For 100% ‘saturation’ the variation in perceived chroma is larger, due to the shape of the sRGB gamut.