CMYK is also called the print color mode. The name suggests is used for printing. It has a big difference compared to RGB: The RGB mode is a glowing color mode in which you can still see the contents of a screen in a dark room; CMYK is a reflective color model. How do we read the newspaper? It is illuminated by sunlight or light on newspapers and reflected in our eyes before seeing the content. It needs external light sources, if you can't read the newspaper in a dark room. Shanghai sticker printing as long as the image displayed on the screen, is the performance of RGB mode. As long as the image is seen on the print, it is the CMYK mode. For example, periodicals, magazines, newspapers, and promotional brochures are all printed. Then it is the CMYK model. Like RGB, CMY is the first letter of the three printing ink names: Cyan Cyan, Magenta Magenta, Yellow Yellow. K takes the last letter of black. The reason why the initial letter is not used is to avoid confusion with blue. In theory, only CMY three inks are sufficient, and three of them should add up to black. However, since the current manufacturing process cannot produce high-purity ink, the result of the CMY addition is actually a dark red color. Therefore, it is necessary to add a special black ink to reconcile.