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Rotationally impervious feature extraction for optical character recognition

  • US 5,054,094 A
  • Filed: 05/07/1990
  • Issued: 10/01/1991
  • Est. Priority Date: 05/07/1990
  • Status: Expired due to Term
First Claim
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1. A feature-based optical character recognition system for extracting features from an individual character image segmented from a document image, comprising:

  • radial intercept feature extraction means for counting a number of intercepts between at least one of a plurality of circles of predetermined radii and boundary transitions in said character image;

    transition point location feature extraction means for determining for each transition point in said image an identity of a pair of regions in a grid superimposed on said character image nearest the transition point, whereby said number of intercepts and said identity of said pair of regions comprise an input data string; and

    feature-based recognition means for comparing said input data string with a set of reference data strings corresponding to a set of known symbols.

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