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Image pre-processor for character image recognition system

  • US 5,818,978 A
  • Filed: 01/27/1997
  • Issued: 10/06/1998
  • Est. Priority Date: 04/15/1994
  • Status: Expired due to Term
First Claim
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1. An image processing apparatus for de-skewing an image of a document, the image comprised by pixels arranged into rows and columns, said apparatus comprising:

  • measuring means for measuring skew angle of the image;

    rotation-transforming means for rotation-transforming pixels of the image by a mathematical rotation transformation so as to reduce the skew angle to approximately zero;

    pixel-shifting means for pixel-shifting columns of the image so as to reduce the skew angle to approximately zero; and

    determination means for causing said rotation-transforming means to reduce skew angle in a case where the measured skew angle is greater than a predetermined limit, and for causing said pixel-shifting means to reduce skew angle in a case where the measured skew angle is less than the predetermined limit.

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