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System and method for enhancing document images

  • US 6,771,838 B1
  • Filed: 10/06/2000
  • Issued: 08/03/2004
  • Est. Priority Date: 10/06/2000
  • Status: Expired due to Fees
First Claim
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1. A method of enhancing a digital image comprising:

  • receiving an input digital image having a non-uniform illumination characteristic, said input digital image including at least one feature;

    detecting edges of said feature of said input digital image;

    generating an estimated illumination surface of said input digital image based on selected pixel luminance values of edge pixels associated with said feature of said input digital image, including collecting statistical values of said edge pixels for each predefined section of said input digital image, said statistical values including a value selected from the group consisting of;

    the number of said edge pixels, the maximum luminance value for said edge pixels, the sum of luminance values of said edge pixels, and the sum of squared luminance values of said edge pixels; and

    selectively adjusting pixel values of said input digital image using said estimated illumination surface to modify said non-uniform illumination characteristic of said input digital image.

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