Accelerating non-local denoising with a patch based dictionary

  • Authors:
  • Hemalata Bhujle;Subhasis Chaudhuri

  • Affiliations:
  • Indian Institute of Technology Bombay, Mumbai, India;Indian Institute of Technology Bombay, Mumbai, India

  • Venue:
  • Proceedings of the Eighth Indian Conference on Computer Vision, Graphics and Image Processing
  • Year:
  • 2012

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Abstract

Nonlocal means (NLM) image denoising algorithm is not feasible in many applications due to its high computational cost. High computational burden is due to the search of similar patches for each reference patch in the entire image. In this paper, we present a novel technique of preselecting and grouping the similar patches in the form of a dictionary and hence speeding up the computation of NLM denoising method. We build a dictionary only once, with a set of training images of all possible classes of objects, in which patches with similar photometric structures are clustered together. For each noisy patch, similar patches are searched in the global dictionary. In contrast with previous NLM speedup strategies, our dictionary building approach preclassifies similar patches with the same distance measure as used by NLM method. We achieve a substantial reduction in computational time than the original NLM method especially when search window of NLM is large, without much affecting the PSNR. The proposed algorithm is shown to outperform other prefiltering based fast NLM algorithms computationally as well as qualitatively.