Direct gravure is a way of transferring a drawing or computer printout on Mylar or another transparent or translucent material to a printing plate. The plate is coated with a photosensitive ground and the Mylar drawing is pressed against it and exposed to light. A textured Mylar is available with tooth built into it, but normally, before etching, direct gravure requires the addition of aquatint or some other way of providing tooth in the marked areas.
Photogravure transfers a photograph onto a metal plate where it etches to various depths. In the darkroom, the printer creates a positive transparency of the image, transfers it to photosensitive gelatin tissue, adheres that to a plate, and develops the image in hot water. Exposure to bright light hardens the ground in varying degrees and allows the darker areas to be very deeply etched into the plate. We usually add an aquatint ground before etching. In photogravure the dark areas of the image, in varying degrees, are physically deeper in the plate than the light areas.