The Yxy color space expresses the Xyz color space in a different way, in terms of only x and y coordinates which allows for a 2d representation.
Hsv (also known as Hsb) is similar to Hsl. They're both based on cylindrical geometries, but Hsv is based on a "Hexacone" model while Hsl is based on a "Double Hexacone" model. Read more about the differences on wikipedia.
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Color conversions performed using the open source ColorMine library.