1. A system for estimating an illuminant of a scene that was captured by an input image that includes a plurality of input colors, the system comprising: a control system that generates an input gamut organized as a matrix having a plurality of rows and a plurality of columns that includes the input colors for the input image, the control system including an illuminant database having a separate illuminant gamut of the observable colors for each of a plurality of potential illuminants, each illuminant gamut being expressed as a matrix having a plurality of rows and a plurality of columns; and the control system compares the input gamut organized as the matrix with the plurality of rows and columns to the illuminant gamut organized as the matrix with the plurality of rows and columns for each of the potential illuminants, wherein the control system combines the input gamut with each of the illuminant gamuts to generate a separate union gamut for each of the possible illuminants, wherein each union gamut is organized as a matrix having a plurality of rows and a plurality of columns.