DCS DCS is called Desktop Color Separation - desktop color separation format. It is a variation of the EPS format produced by Quark for making color separation easier. The original DCS format (version 1) contains five files. The dominant file is a color low resolution EPS graphic. Used to see samples. Four other files have blue, black, yellow, and black color separation signals. Each is a black-and-white image (because color separation information includes color information.) When Quark prints a color separation sheet, it uses the correct separation file in the DCS image. The dominant file includes each separation. Note for the file. Because of file naming issues, there is a certain problem with the use of DCS version 1 between Mac and DOS systems. DCS version 2 expands the capabilities supported for spot color editions and allows DCS's single file format. A single file format is just a separation file with a description of the file header. Data separation must be performed before printing. OPI OPI is called Open Pre-Press Interface, which is an open prepress interface. It was invented by Aldus. OPI is not a file format, but a way to work with smaller files to speed up the DTP production process. It is also a fake of the EPS file. For a 10MB or higher capacity EPS file, a small size of a few KB can be used instead to speed up the work process. In OPI, images are placed in the system and processed by the OPI input processor. OPI technology can place the original image somewhere, and then use a smaller image to replace it in order to achieve the preview effect. The DTP program cannot see the PS code in the EPS file except for the EPS header comment. It can only use the preview image data of the EPS file. When printing, the complete code for the EPS file is placed in the print file. The OPI operates by removing all the contents of the EPS file, leaving the file header in place, and adds a special note where it can be recognized to describe the address reserved by the original EPS file. If the file is to be printed, it must go through the OPI processor, look for inserted comments, and use the original file data. For the preview part in the EPS, it is a bitmap drawing using the screen resolution; the dominant file in the DCS is suitable for the look of the PS file; the OPI produces the stub file. When printing pages using OPI images, make sure that the OPI can return to the original image. Many systems can automate this process, but sometimes it is possible to print the file directly to the printer. If the stub file does not extend the image part, there will be an image blank. In some OPI systems, there will be a rough display image of the original image, which will also print out the basic effects.