Any of several processes for producing printing plates by photographic means (see photography). In general, a plate coated with a photosensitive substance is exposed to an image, usually on film; the plate is then treated in various ways, depending on the printing process to be used. Photoengraving is particularly useful for reproducing photographs via the halftone process. See also offset printing
Making printing plates by exposure of line and halftone negatives on sensitized metal, converting the image into an acid resist, and etching the print to the relief required for letterpress printing
A process for making relief plates by using acid to etch away the non-printing areas of a photographically produced image The subject is photographed through a wire or glass screen, which breaks the light in a way that sensitizes the metal plate in a dotted pattern Darker areas are created with larger dots while highlights are rendered with finer dots When printed, the finest screens create the most precise detail This process was used principally for reproducing illustrations in the earlier part of the 20th century