It's extremely hard to explain with words, so I hope the image says it all:
The standard HSL color model looks like the image on the left.
Depending on which angle from your screen you look at it (im my case it's always visbile but more when looking from the bottom), you can clearly see that there is a horizontal line in the middle of the image. It's in fact just a difference in how it transitions, but the human eye/brain somehow makes a "line" of it. In addition, there are 3 such vertical lines, between the red and green, between the green and blue, and in the purple zone.
The red markings in the centermost image contain where those ugly lines are.
And the rightmost image shows a plot of a mathematical function (guess which) made with that very HSL color model. And there it is, the ugly line is visible there as well.
I'd like to make better looking plots. It should still be a HSL-like color model: still black at the bottom, white at the top (HSV is not white at the top), and all hues in the center. But smoothed in some way that no such obvious lines are visible.
I now use the standard HSL to RGB conversion function I already tried, after HSL to RGB, to set Y to the lightness with RGB->YUV->RGB conversion, but that looks even uglier, yellow becomes olive.
Does anyone know:
If there's a trick to make HSL color better for such mathematical plotting purpose?
What the phenomenon with the "lines" is called?
Another more suitable color model?