Identifying facsimile duplicates using radial pixel densities

Abstract.

A method for detecting full layout facsimile duplicates based on radial pixel densities is proposed. It caters for facsimiles, including text and/or graphics. Pages may be positioned upright or inverted on the scanner bed. The method is not dependent on the computation of text skew or text orientation. Using a database of original documents, 92% of non-duplicates and upright duplicates as well as 89% of inverted duplicates could be correctly identified. The method is vulnerable to double scanning. This occurs when documents are copied using a photocopier and the copies are subsequently transmitted using a facsimile machine.