Patent Document ID: 7616810
Application ID: 12049255
Patent Status: 1

Claim One:
1. A method for estimating an image illuminant, the method comprising: forming a design matrix for a set of model illuminants, said design matrix comprising chromaticity coordinates for said model illuminants; computing a Moore-Penrose pseudoinverse of said design; generating an image histogram for an image; determining match scores for said model illuminants with said image histogram; determining a match score minimum value from said match scores; determining match score minimum value chromaticity coordinates; computing a parameter vector for a surface fit to said match scores, wherein said parameter vector is determined with said Moore-Penrose pseudoinverse of said design matrix and a vector of said match scores; determining an extremum of said surface fit to said match scores wherein said extremum is determined using partial derivatives with respect to chromaticity coordinate axes; determining chromaticity coordinates of said extremum; if said extremum chromaticity coordinates are closer to the coordinates of a model illuminant than said match score minimum value chromaticity coordinates, selecting said extremum chromaticity coordinates as image illuminant coordinates; if said extremum chromaticity coordinates are not closer to the coordinates of a model illuminant than said match score minimum value chromaticity coordinates, selecting said match score minimum value chromaticity coordinates as image illuminant coordinates; wherein said computing steps and said determining steps are performed by at least one computing device.