CTP(Computer to plate)：From the computer directly to the plate, that is, offline direct plate making. Originally developed from photographic direct plate making, all the computer-controlled laser scanning imaging, and then through the development, fixing and other processes plate printing. This technique eliminates film as an intermediate medium, directly converts text and image into numbers, and reduces the quality loss and material consumption of the intermediate process. The usual CTP version is this one.

Since the 1960s edition of PS was applied to offset printing, offset printing process has been used in the prepress process of photosensitive negatives, imposition, printing and PS printing. In order to speed up the speed of plate making, reduce the loss of intermediate links and nodes and improve the quality of printing, in the late 1970s, some companies in the United States and Japan began to develop and develop CTP (Computer- to-plate) systems and materials, and formed primary products in 1980s. After entering 90s, the technology of CTP has developed rapidly. It is in the stage of popularization and application.