Method of quantifying the quality of a gray scale image of a document and an apparatus therefor

Abstract

A method of processing a document comprises the steps of (a) scanning a document to obtain gray scale image data associated with the document, (b) generating a two-dimensional histogram based upon the gray scale image data obtained in step (a), (c) applying a clustering algorithm to the two-dimensional histogram to determine a set of cluster center parameters associated with a first cluster of pixels and a set of cluster center parameters associated with a second cluster of pixels, (d) determining the standard Euclidean distance between the sets of cluster center parameters, and (e) normalizing the distance determined in step (d) to provide a value indicative of the quality of the document. The normalized result in step (e) may be a value between zero and one, and the algorithm includes a k-means clustering algorithm. The one cluster of pixels is representative of background of the document and the other cluster of pixels is representative of foreground of the document. One cluster of pixels is located above the other cluster of pixels. The above cluster of pixels is representative of background of the document and the other cluster of pixels is representative of foreground of the document.