CTP includes the following four meanings in the printing field. Computer to Plate: From the computer directly to the plate, that is, people often say "offline direct plate." It was originally developed from photographic platemaking. All platemaking equipment is computer-controlled laser scanning imaging, and then developed into a printing plate through processes such as development and fixing. This technology enables the conversion of text and images into digital images, eliminating the intermediate medium of film and reducing the quality loss and material consumption of intermediate processes. Computer to Press: Directly from the computer to the printing press, which is often referred to as "in-machine direct printing." It is to install the printing plate on the cylinder of the digital printing machine, then through the computer-controlled laser beam, the graphic information is directly output to the printing plate, and then the printing is started. At present, this type of printing plate can record images, but it cannot be wiped off and it can only be used once. Computer to Paper/Print: Directly from the computer to paper or prints. Computer to Paper is equivalent to ink-jet printing, that is, computer-controlled inkjet heads. The ink droplets are directly printed on the paper to form graphic information. Computer to Print is equivalent to a computer-controlled laser beam to output graphic information directly to the "printing plate" and you can start printing. · Computer to Proof: Get proofs directly from the computer, digital proofing. Digital proofing is an important part of the digital control process in the prepress area. Its purpose is to verify the quality of the printed product and the degree of customer recognition of the print effect. Due to the low price and high efficiency, digital proofing is gradually replacing part of the traditional analog proofing. With the development of CTP technology, CTcP technology (Computer To conventional Plate), which is an ordinary PS plate direct plate making technology, is now emerging, and it is launching powerful challenges to the traditional CTP technology. Under normal circumstances, CTP technology refers more to computer to plate (Computer to Plate) technology.