Patent ID: 7081920

Claim:
A method of estimating an illumination light color using three primary color signals to obtain white balance, comprising: acquiring average values of the three primary color signals from an image sensing element, the three primary colors having signal levels equalized with respect to illumination light having a predetermined color temperature in a predetermined image sensing area of the image sensing element; setting the signal with the higher level, of red and blue signals contained in the average values, as a signal of interest; reducing the red or blue signal in the signal of interest together with a green signal at the same ratio when the green signal is larger than a value obtained by dividing a resultant value by the green signal, and reducing the red or blue signal in the signal of interest when the green signal is smaller than the resultant value, the resultant value being obtained by multiplying the red signal by the blue signal; and obtaining a white point at which a geometric average of the red and blue signals obtained by the reduction processing has the same level as that of the green signal and estimating a color corresponding to the white point as the illumination light color.