Shades of cyan 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 cyan 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 cyan ink. A typical formulation of "process cyan" is shown in the color box at right. The source of the color shown at right is the color magenta that is shown in the diagram located at the bottom of
Color printing through "color separation," and "screening" or "halftoning." These steps make possible the creation of printing plates that can transfer color impressions to paper on printing presses based on the principles of lithography. An emerging method of full-color printing is six-color process printing (for example, Pantone's Hexachrome system) which adds orange and green to the traditional CMYK inks for a larger and more vibrant gamut, or color range. However, such alternate color systems still rely on color separation, halftoning and lithography to produce printed images. Color printing can also involve as few as one color ink, or multiple color inks which