Over a wide range of conditions of observation, many colours can be matched completely by additive mixtures in suitable amounts of three fixed primary colors. The choice of three primary colors, though very wide, is not entirely arbitrary. Any set that is such that none of the primaries can be matched by a mixture of the other two can be used. It follows that the primary colour vectors so defined are linearly independent.

Therefore, transformations of a metameric match from one colour space to another can be predicted via a matrix calculation. The limitations of colour gamut apply to each space. The additive colour generalisation forms the basis of most image capture, and of most self-luminous displays (i.e., CRTs, etc.).