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Method of indexing words in handwritten document images using image hash tables

  • US 5,953,451 A
  • Filed: 06/19/1997
  • Issued: 09/14/1999
  • Est. Priority Date: 06/19/1997
  • Status: Expired due to Term
First Claim
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1. A method of localizing handwritten words in an image of a document, comprising:

  • a) pre-processing a document containing handwriting where curves with features for word localization are extracted from handwritten words contained in the document, wherein each curve includes selected features with the selected features being less than all of the features for the curve;

    b) grouping the curves to form curve groups;

    c) computing basis triples from the selected features of the curves of the curve groups;

    d) computing affine coordinates for the features of the curves in each curve group with respect to corresponding basis triples computed with said (c);

    e) using the affine coordinates and basis triples to create an image hash table with entries for indexing the handwritten words of the document, wherein the image hash table includes a list of the basis triples;

    f) indexing the handwritten words with the image hash table, wherein query word features are used to look up the handwritten words in the image hash table for candidate locations; and

    g) verifying registration of underlying words within the image hash table by projecting a query word onto one of the underlying words at the candidate locations to find a match.

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