Patent ID: 7164797

Claim:
A clustering system comprising: a mark extractor to extract a mark from a document; a match component operative to compare one or more properties of the mark to one or more match properties of existing clusters of marks so as to identify matching existing clusters, the match properties comprising resized images for the existing clusters, and the match component operative to compute a range of acceptable values for the one or more properties using a threshold; a two dimensional table that stores the existing clusters according to box size, wherein if no matches are identified, the mark is added to the existing clusters as a new cluster, and if a match is identified then bitmaps of the mark and the matching existing clusters are compared; and a match symbol component operative to compare a bitmap of the mark to a bitmap of the matching existing clusters the bitmaps are compared bit by bit to identify a matching cluster having a similar bitmap, wherein once an acceptable matching cluster is identified based on the bitmaps, the bitmap of the matched cluster is updated with an average based on the bitmap of the mark, and if no matching cluster is acceptable based on the bitmaps, the mark is added to the existing clusters as a new cluster.