Method of nonlinear filtering of degraded document images

Details Method of nonlinear filtering of degraded document images Method of nonlinear filtering of degraded document images

1994-07-28

1997-07-08

Boudreau, Leo

Image analysis

Pattern recognition

Template matching

382261, 382275, G06K 962

Patent

active

056470231

ABSTRACT:
A method identifies and models the distortion in a document using a two-dimensional nonlinear filter. The two-dimensional nonlinear filter is then used to improve the performance of optical character recognition systems in recognizing characters in documents that have been degraded, as for example by repeated photocopy reproductions or by fax transmission.

REFERENCES:
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patent: 5490223 (1996-02-01), Nishimura et al.
S. Mori et al., "Historical Review of OCR Research and Development," Proceedings of the IEEE, vol. 80, No. 7, 1029-1057 (Jul. 1992).
V.K. Govindan et al., "Character Recognition--A Review," Pattern Recognition, vol. 23, No. 7, 67--683 (1990).
C.F.N. Cowan et al., "Non-Linear System Modelling: Concept and Application," Proc. 1984 ICASSP, 4561-4564 (1984).
T. Endoh et al., "Progressive Reduction Standard for Bi-level Images," JBIG-ISO JTCI/SC2/WG8 CCITT SG VIII (Jul. 1989).
L. O'Gorman, "Image and Document Processing Techniques for the RightPages Electronic Library System," Proc. 1992 Int'l. Conf. on Pattern Recognition, vol. II, 260-263 (1992).
Patent Abstracts of Japan, vol. 14, No. 494, Japan (P-1123), Oct. 26, 1990 & JP-A-02-202689 (Fujitsu Ltd) Aug. 10, 1990, abstract.
Patent Abstracts of Japan, vol. 15, No. 368 (P1235), Japan Sep. 17, 1991 & JP-A-03 144788 (Nec Corp) Jun. 20, 1991, abstract.

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