Patent ID: 6650774
Filing Date: 2003-11-18
Classification: G06T

Abstract:
A computer-implemented process for improving the uniformity in exposure and tone of a digital image, said process comprising using a computer to perform the following acts:segmenting the digital image into a plurality of image patches; for each image patch, creating a pixel brightness level histogram which identifies a respective pixel count for each of a plurality of original pixel brightness levels exhibited by the pixels of the patch; averaging said pixel brightness level histogram with the histograms associated with a prescribed number of neighboring image patches to produce an averaged histogram; for each image patch, generating a normalized cumulative distribution function based on the histogram, wherein a maximum cumulative count value thereof corresponds to a maximum original pixel brightness level, and wherein said normalized cumulative distribution function identifies a respective new pixel brightness level for each of the original pixel brightness levels as represented by the normalized pixel count value corresponding to each respective original pixel brightness level; for each image patch, respectively blending the new pixel brightness level associated with each of the original pixel brightness levels with the new pixel brightness level associated with the same original pixel brightness level in at least one neighboring image patch; and for each image patch, replacing the original pixel brightness level of each pixel in the image patch with the blended pixel brightness level corresponding to that original brightness level, to produce a final image exhibiting improved uniformity in exposure and tone.