Patent ID: 7206072

Claim:
A light source type discriminating method for discriminating a light source type of a photographic light source, comprising the steps of: providing first to third sensors respectively having spectral sensitivities corresponding to three primary colors; arranging a fourth sensor having a spectral sensitivity that does not overlap said spectral sensitivities corresponding to said three primary colors, said first to fourth sensors constituting an image pickup system; and discriminating said light source type of said photographic light source by using information obtained by said first to fourth sensors, wherein: said fourth sensor is a sensor in which a value of an average minimum distance L min indicating light source similarity between respective light sources whose types are to be discriminated is at least equal to a predetermined first reference value, said average minimum distance L min being represented by an expression: L min =ΣL ( i ) j min /m (1) where L min is the average minimum distance, L(i)j is a similarity between a reference light source (i) and another light source (j) and m is a number of types of light sources, and being obtained based on differences between respective sensor signals of said reference light source (i) and respective sensor signals of said another light source (j).