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Method for estimating and adjusting digital image contrast

  • US 5,822,453 A
  • Filed: 12/10/1996
  • Issued: 10/13/1998
  • Est. Priority Date: 12/10/1996
  • Status: Expired due to Fees
First Claim
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1. A method of estimating the scene contrast from a digital image, the method comprising the steps of:

  • a) determining a Laplacian value for value for each pixel of the digital image;

    b) forming a Laplacian histogram distribution based on the Laplacian values;

    c) determining, from the Laplacian histogram, first and second thresholds which eliminate substantially uniform areas or substantially textured portion of the digital image;

    d) selecting pixels which are based on the first and second thresholds from the digital image;

    e) forming an intensity histogram from the selected pixels;

    f) computing a standard deviation of the intensity histogram; and

    g) estimating contrast of the digital image by comparing the computed standard deviation with a predetermined contrast for determining contrast of the input image in relationship with the predetermined contrast.

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