Imagine a chromaticity diagram, but on a perceptual color space where long-range euclidean distance at least attempts to describe the magnitude of perceived dif

Imagine a chromaticity diagram, but on a perceptual color space where long-range euclidean distance at least attempts to describe the magnitude of perceived difference (rather than the usual model artifacts) - so round-ish. Then decreasing perceived difference between red and green shows up as a smush to oval.