US Patent 9307214 Automatic white balance methods and systems for electronic cameras

A brightness-sensitive automatic white balance method includes (a) determining the brightness of a scene captured in an electronic color image, (b) selecting a color-weighting map based upon the brightness of the scene, (c) extracting auto white balance parameters from the color-weighting map, and (d) white balancing the electronic color image according to the auto white balance parameters. An adaptive automatic white balance method includes (a) refining, based upon a first electronic color image of a scene illuminated by an illuminant of a first spectral type, a color-weighting probability distribution for the illuminant of the first spectral type, wherein the color-weighting probability distribution may be brightness-specific, (b) extracting auto white balance parameters from the refined color-weighting probability distribution, and (c) white balancing, according to the auto white balance parameters, an electronic color image of a scene illuminated by the illuminant of the first spectral type.