XYB color space
A visualization of the XYB color space, which is used in (lossy) JPEG XL and based on LMS, a color space modeling the responses of the three types of cone cells. The horizontal axis is X, which is based on L-M (red-green). The vertical axis is B, which is based on S (blue-yellow). Slices of XYB with constant Y are shown, for increasing Y (which is based on L+M and roughly corresponds to luminosity).