Enhancing degraded document images via bitmap clustering and averaging

Proper display and accurate recognition of document images are often hampered by degradations caused by poor scanning or transmission conditions. The authors propose a method to enhance such degraded document images for better display quality and recognition accuracy. The essence of the method is in finding and averaging bitmaps of the same symbol that are scattered across a text page. Outline descriptions of the symbols are then obtained that can be rendered at arbitrary solution. The paper describes details of the algorithm and an experiment to demonstrate its capabilities using fax images