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Method and apparatus for text detection

  • US 6,778,700 B2
  • Filed: 03/14/2001
  • Issued: 08/17/2004
  • Est. Priority Date: 03/14/2001
  • Status: Expired due to Term
First Claim
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1. A method having scanned intensity information as input for detecting text in a scanned page by observing a very strong contrast in a localized region that comprises a substantially sharp edge between a dark side and a light side, the method comprising:

  • pre-processing by detecting a local ramp, identifying an intensity trough, and determining a stroke width, wherein local ramp detection comprises using a threshold value and nine 3×

    3 high-pass filters to obtain nine filtered values per pixel, and determining therefrom any of a vertical ramp detection value, a horizontal ramp detection value, a diagonal ramp in vertical direction detection value, and a diagonal ramp in horizontal direction detection value; and

    contrast-based text detection processing, whereby any of black text on white background, black text on color background, and white or light text on a dark background are detected.

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