Under color removal Under color removal In printing, under color removal (UCR) is a process of eliminating overlapping yellow, magenta, and cyan that would have added to a dark neutral (black) and replacing them with black ink only, called a "Full Black", during the color separation process. Under color removal is used in four-color (or more colors) printing. Black ink used to add details and darkness in shadowed areas is called a "Skeletal Black". With current ink technology, the total CMYK ink in the shadows refuses to stick after it reaches the dark shadows (usually above a 250% total CMYK coverage), and begins
RGB color model plasma, OLED, quantum dots, etc.), computer and mobile phone displays, video projectors, multicolor LED displays and large screens such as JumboTron. Color printers, on the other hand are not RGB devices, but subtractive color devices (typically CMYK color model). This article discusses concepts common to all the different color spaces that use the RGB color model, which are used in one implementation or another in color image-producing technology. To form a color with RGB, three light beams (one red, one green, and one blue) must be superimposed (for example by emission from a black screen or by reflection from a