In a system employing three colour primaries to encode image color, each primary can be located on a CIE chromaticity diagram and these points connected as a plane figure. If the apexes are then connected with an appropriate value on the white point axis, a so) id figure is produced enclosing the colour gamut for that system. (On the CIE chromaticity diagrams, the points in x, y, z space approximate an inverted tetrahedron.

In u, v, w space, they become a somewhat irregular four-cornered solid.) colours within the colour gamut solid volume can be reproduced by the system as metameric matches. colours outside the colour gamut solid volume cannot be matched. Note: The area of the cross-section from the colour gamut solid is a function of the luminance. Although it is advantageous to have the widest possible colour gamut for the ability to provide metameric matches for the largest number of colors, the required transformations from origination colorimetry to colorimetry matched to available display primaries, for example, may require large matrix coefficients and, therefore, a signal-to-noise penalty. The choice of colour gamut is a compromise between colour rendition and signal-to-noise.