Abstract: A mounting and proofing apparatus has plate and layout cylinders rotatably mounted in a frame in parallel alignment to each other. A partial mirror is disposed proximate the plate and layout cylinder to permit a user looking into the partial mirror to view superimposed images of the layout and plate cylinders. At least one video camera is disposed above and directed at the partial mirror to image the superimposed images upon a video display having radicle markings. A layout sheet is installable on the layout cylinder indicating proper positioning of printing plates on the plate cylinder. The video camera optionally magnifies superimposed images of registration marks on the layout sheet and the plate cylinder. The user aligns the radicle with the registration mark, places a printing plate on the imaged area of the plate cylinder, and then aligns corresponding registration mark on the printing plate with that of the layout sheet.

Abstract: The positions of horizontal lines on a layout cylinder of a printing plate mounting and proofing machine are located with automatic compensation for stretch that results from various parameters such as the diameter of a printing cylinder on which the layout will be used, and the thicknesses of the printing plates and printing plate backing. A display of the circumferential displacement of the layout cylinder, as the cylinder is rotated, provides the displacement with the necessary compensation for stretch, rather than the actual cylinder displacement.