In computer graphics, the gamut is a certain complete subset of colors.
The most common usage refers to the subset of colors which can be accurately
represented in a given circumstance, such as within a given color
space or by a certain output device. Another sense, less frequently
used but not less correct, refers to the complete set of colors found
within an image at a given time.
Gamuts are commonly represented as areas in the CIE 1931 chromaticity
diagram below, with the curved edge representing the monochromatic colors.
These areas typically have triangular shapes.
However, the accessible gamut depends on the brightness; a full gamut
must therefore be represented in 3D space, as below.
The cone drawn in grey corresponds roughly to the CIE diagram above,
with the added dimension of brightness.
The axes in the following diagrams are the responses of the short-wavelength,
middle-wavelength, and long-wavelength cones in the human eye. The other
letters indicate black, red, green, blue, cyan, magenta, yellow, and white
The diagram above shows that the shape of the RGB gamut is a triangle
between red, green, and blue at lower luminosities; a triangle between
cyan, magenta, and yellow at higher luminosities, and a single white point
at maximum luminosity. The exact positions of the apexes depends on the
emission spectra of the phosphors in the computer monitor, and on the
ratio between the maximum luminosities of the three phosphors (i.e., the
The gamut of the CMYK color space is, ideally, approximately the same
as that for RGB, with slightly different apexes, depending on both the
exact properties of the dyes and the light source. In practice, due to
the way raster-printed colors interact with each other and the paper and
due to their non-ideal absorption spectra, the gamut is smaller and has
The gamut of reflective colors in nature has a similar, though more
rounded, shape. An object that reflects only a narrow band of wavelengths
will have a color close to the edge of the CIE diagram, but it will have
a very low luminosity at the same time. At higher luminosities, the accessible
area in the CIE diagram becomes smaller and smaller, up to a single point
of white, where all wavelengths are reflected exactly 100 per cent. The
exact coordinates of white are of course determined by the color of the