Auto white balancing by modified grey world and geometric distortion measurement

Abstract

A method, apparatus and computer program product for correcting white balance in a digital image are described. The method comprises determining a number of grey blocks in the digital image (s), each block comprising a subset of pixels of the image, and if the number of grey blocks is less than a predetermined value, scaling one or more color channels of the digital image using a first gain value to generate a first intermediate image (sA) and scaling one or more color channels of the digital image using a second gain value to generate a second intermediate image (sB). A number of grey blocks in each of the first and second intermediate images (sA, sB) is determined and the gain value resulting in the intermediate image having a greater number of grey blocks is set as the reference gain value (s). A grey world process is performed on the intermediate image having a greater number of grey blocks (s). Also described are a method, apparatus and computer program product for computing gain values for correcting a white balance of a digital image. The method comprises receiving an image divided into a number of blocks, removing the three most frequently occurring colors from the image (s), and scaling one or more color channels of the image by respective reference gain values derived by a grey world process performed on the image.