Patent ID: 7146041

Claim:
A white balance correction method, comprising the steps of: estimating, by using at least gray and/or skin color information contained in an input color image, a color temperature of a photographing light source with which the color image has been taken; and correcting image signals of the color image based on the estimated color temperature, wherein said estimating step includes: multiplying the image signals of respective pixels in the input color image by set coefficients; setting pixels having the multiplied image signals in the vicinity of blackbody locus curve of skin color as skin color candidate pixels and pixels having the multiplied image signals in the vicinity of a blackbody locus curve of gray as gray candidate pixels; optimizing the set coefficients so that the number of the skin color candidate pixels and/or gray candidate pixels is maximized and a difference between an average color temperature of the group of skin color candidate pixels and the group of gray candidate pixels is minimized; obtaining a group of skin color candidate pixels and a group of gray candidate pixels by using the optimized coefficients; dividing the group of skin color candidate pixels into a plurality of subgroups of skin color candidate pixels and dividing the group of gray candidate pixels into a plurality of subgroups of gray candidate pixels; and estimating a color temperature of the photographing light source from an average color temperature of a subgroup of skin color candidate pixels with a high average color temperature among the plurality of subgroups of skin color candidate pixels and an average color temperature of a subgroup of gray candidate pixels with a high average color temperature among the plurality of subgroups of gray candidate pixels, and wherein the color image signals multiplied by the optimized coefficients are corrected by a difference between the estimated color temperature and a color temperature of reference white.