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 by coordinates, which in 1931 were also named in global agreement with internationally agreed color names like mentioned above (red, orange, etc.) by the International Commission on Illumination. The RGB color space for instance is a color space corresponding to human trichromacy and to the three cone cell types that respond to three bands of light: long wavelengths, peaking near 564–580 nm ("red"); medium-wavelength, peaking near 534–545 nm ("green"); and short-wavelength light, near 420–440 nm ("blue"). There may also be more than three color dimensions in other color spaces, such as in the CMYK color model, wherein one of the