Automatic white balance method and apparatus

Abstract

Automatic white balance of captured images can be performed based on a gray world assumption. Initially, a flat field gray image is captured for one or more reference illuminations. The statistics of the captured gray image are determined and stored for each reference illumination during a calibration process. For each subsequent captured image, the image is filtered to determine a subset of gray pixels. The gray pixels are further divided into a one or more gray clusters. The average weight of the one or more gray clusters is determined and a distance from the average weights to the reference illuminants is determined. An estimate of the illuminant is determined depending on the distances. White balance gains are applied to the image based on the estimated illuminant.

Description

[0001] Related Application Cross Reference [0002] This application claims rights based on U.S. Provisional Application No. 60 / 583,144, filed June 25, 2004, and entitled "Method and Apparatus for Automatic White Balance," which The US Provisional Application is hereby incorporated by reference in its entirety. technical field [0003] The present invention provides a method and device for performing automatic white balance (AWB), and particularly relates to the technical field of performing automatic white balance on captured images according to a gray world assumption. Background technique [0004] Illumination sources - also referred to herein as illuminants - are usually not pure white, but biased toward a specific color. The color shift is usually measured in color temperature. The human eye compensates for lighting that is not pure white, so colors appear relatively consistent under a wide variety of lighting conditions. However, the electronic sensors used to captu...

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