CTP methods differ according to the construction type of the imagesetter and the light source used to expose the plate surface. In terms of construction type there are three different kinds: internal drum, external drum and flat-bed imagesetters. The two main light sources used to expose the plate are ultraviolet light lamps and laser diodes. The wavelength and energy of the laser diodes depend on the type of plate that is used. This technology is mainly use in newspaper and magazine printing.
Computer to plate (CTP) is an imaging technology used in modern printing processes. In this technology, an image created in a Desktop Publishing (DTP) application is output directly to a printing plate.