Patent ID: 8213735

Claim:
A method of processing a first set of pixel values corresponding to a portion of an image, the first set of pixel values including multivalent pixel values, each multivalent pixel value corresponding to a pixel-value location in the portion of an image, the method comprising: performing a first filtering operation on said first set of pixel values to generate a second set of pixel values, each pixel value in said second set of pixel values being not less than a corresponding pixel value in the first set; performing a second filtering operation on said first set of pixel values to generate a third set of pixel values, each pixel value in said third set of pixel values being not more than a corresponding pixel value in the first set; using a processor to determine, for each of a plurality of pixel value locations in said portion of an image, a bivalent pixel value, based on the corresponding pixel values in at least two of said first, second and third sets of pixel values; and storing in a storage device, a set of determined bivalent pixel values corresponding to said portion of an image.