CMYK color model color reproduction and they may be viewed as the inverse of RGB. Cyan absorbs Red, Magenta absorbs Green, and Yellow absorbs Blue (-R,-G,-B). Since RGB and CMYK spaces are both device-dependent spaces, there is no simple or general conversion formula that converts between them. Conversions are generally done through color management systems, using color profiles that describe the spaces being converted. Nevertheless, the conversions cannot be exact, particularly where these spaces have different gamuts. The problem of computing a colorimetric estimate of the color that results from printing various combinations of ink has been addressed by many scientists. A general
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