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Method and apparatus for noise reduction

  • US 5,461,655 A
  • Filed: 06/11/1993
  • Issued: 10/24/1995
  • Est. Priority Date: 06/19/1992
  • Status: Expired due to Term
First Claim
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1. A method for reducing noise in a digital image represented by an array of pixel values by processing said image, said processing comprising the steps of:

  • a) decomposing said image into a multiresolution representation comprising a set of detail images at multiple resolution levels and a residue,b) estimating the noise level in each detail image or recalling said noise level from a noise table comprising predetermined typical noise level values corresponding to detail images with similar noise statistics;

    c) establishing a local observation neighborhood around each pixel of each detail image and estimating local image content within said neighborhood,d) pixelwise attenuating the detail images as a function of the estimated amount of image content and in accordance with said estimated noise level,e) computing said processed image by applying a reconstruction algorithm to the residue and to the attenuated detail images, said reconstruction algorithm being such if it were applied to the residual image and the detail images without attenuation, then said digital image or a close approximation thereof would be obtained.

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