Are H/S/L values on color picker in HSL or HSLuv?

[joliss]

I think the H/S/L values at the bottom of the color picker page are in HSLuv, rather than HSL, but I'm a bit confused. I could also see it being HSL, in which case the color picker simply demonstrates the CIELUV space, and gives us HSL/RGB coordinates to copy into our design tools.

I think part of the reason I'm confused is that I'm seeing a circle in the diagram, but adjusting the hue moves the color dot in straight lines. So now I'm not sure what the circle is supposed to mean.

Could it be worth clarifying whether it's HSL or HSLuv on the page, and perhaps what the circle does?

[boronine]

Sorry for the delay, I thought I would actually fix this but I'm not sure I have time right now. Just to answer your question, the sliders on the homepage represent the H, S, L components of the HSLuv color space, not HSL.

The oddly shaped polygon in the picker is indeed CIELUV, or rather its cylindrical form, also known as CIELUV LCh. This is a bit confusing because one might expect the demo to show HSLuv instead. If you want to imagine what HSLuv would look like in that demo, just imagine stretching the polygon in all directions until it fits in the outer circle. Then the hue slider will stop moving in straight lines.

I think showing CIELUV instead of HSLuv makes for a better demo as it explains the relationship between the two, but many people are confused by the homepage, so it definitely needs some work.