Patent ID: 6791606
Filing Date: 2004-09-14
Classification: H04N

Abstract:
An auto white balancing apparatus comprising:(a) a block split circuit for splitting an image into a plurality of blocks; (b) a representative color calculating circuit which for each split block, derives a representative color of each block on the basis of pixel values within each block; (c) a block reliability estimating circuit which for each block determines the distance between color difference components of the color of a white object under at least one light source and color difference components of the representative color of each block, to thereby estimate a reliability signal with which the at least one light source lights a scene of each block on the basis of the distances; (d) a circuit for determining the variance of pixel values of pixels sampled from the block; (e) a circuit for modifying the reliability signal estimated by the block reliability estimating circuit, in accordance with a predetermined function whose value becomes smaller as the variance of the pixel values increases; (f) a lighting color estimating circuit for estimating the color of lighting which lights the scene of the entire image in response to the modified reliability signals; and (g) a white balancing circuit for executing white balance processing of each pixel of the image so as to cancel the estimated lighting color.