Shades of magenta yellow and cyan, constitute the three subtractive primary colors of pigment. (The secondary colors of pigment are blue, green, and red.) As such, the CMYK printing process was invented in the 1890s, when newspapers began to publish color comic strips. Process magenta is not an RGB color, and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color that is pure magenta ink. A typical formulation of "process magenta" is shown in the color box at right. The source of the color shown at
Subtractive color the spectrum. Magenta is the complement of green, and yellow the complement of blue. Combinations of different amounts of the three can produce a wide range of colors with good saturation. In inkjet color printing and typical mass production photomechanical printing processes, a black ink K (Key) component is included, resulting in the CMYK color model. The black ink serves to cover unwanted tints in dark areas of the printed image, which result from the imperfect transparency of commercially practical CMY inks; to improve image sharpness, which tends to be degraded by imperfect registration of the three color elements; and