Patent ID: 7436997

Claim:
A light source estimation apparatus to correctly estimate the image-pickup light source, in which from sensor response values obtained upon pickup of an image of an unspecified arbitrary object, image-pickup means having a plurality of different spectral sensitivity characteristics estimates spectral characteristics indicating color of an unknown image-pickup light source irradiating an object, comprising: storage means for storing, for each test light source, parameters for projecting said sensor response values into an evaluation space not dependent on said image-pickup light source by performing operations which can be colorimetrically approximated from a plurality of different said known spectral sensitivity characteristics of said image-pickup means and from the spectral characteristics of a plurality of test light sources assumed in advance; projection conversion means for projecting said sensor response values into said evaluation space not dependent on the image-pickup light source using parameters stored in said storage means; and, evaluation means for evaluating the correctness of said plurality of test light sources based on the image distribution state of sample values of an image scene projected by said projection conversion means.