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Method for correcting image signal deteriorated by flare and image reading unit

  • US 5,208,874 A
  • Filed: 09/30/1991
  • Issued: 05/04/1993
  • Est. Priority Date: 10/12/1990
  • Status: Expired due to Fees
First Claim
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1. A method for correcting image information deteriorated by flare generated in an image reading unit having a light source for irradiating a document, a scanning system for optically scanning the document irradiated by said light source line by line and outputting the image information, and a reference image having a step shaped density distribution in a direction parallel to each scanning line of said scanning system, said method comprising the following steps (a) through (d) of:

  • (a) optically scanning, with said scanning system, the reference image having a step shaped density distribution irradiated by said light source, and said scanning system outputting reference image information corresponding to the reference image;

    (b) generating a function representing an effect surrounding points have on the density of a specified point, said effect being caused by the flare, using the reference image information obtained by said scanning system in said step (a);

    (c) optically scanning the document irradiated by said light source with said scanning system, such that said scanning system outputs image information of the document; and

    (d) performing a deconvolution operation in which the image information of the document outputted by said scanning system in said step (c) and the function generated by said step (b) are used to calculate corrected image information of the document.

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