Fast separable nonlocal means

Sanjay Ghosh; Kunal N. Chaudhury

doi:10.1117/1.JEI.25.2.023026

25 April 2016 Fast separable nonlocal means

Sanjay Ghosh, Kunal N. Chaudhury

Author Affiliations +

Journal of Electronic Imaging, Vol. 25, Issue 2, 023026 (April 2016). https://doi.org/10.1117/1.JEI.25.2.023026

Abstract

We propose a simple and fast algorithm called PatchLift for computing distances between patches (contiguous block of samples) extracted from a given one-dimensional signal. PatchLift is based on the observation that the patch distances can be efficiently computed from a matrix that is derived from the one-dimensional signal using lifting; importantly, the number of operations required to compute the patch distances using this approach does not scale with the patch length. We next demonstrate how PatchLift can be used for patch-based denoising of images corrupted with Gaussian noise. In particular, we propose a separable formulation of the classical nonlocal means (NLM) algorithm that can be implemented using PatchLift. We demonstrate that the PatchLift-based implementation of separable NLM is a few orders faster than standard NLM and is competitive with existing fast implementations of NLM. Moreover, its denoising performance is shown to be consistently superior to that of NLM and some of its variants, both in terms of peak signal-to-noise ratio/structural similarity index and visual quality.

Citation Download Citation

Sanjay Ghosh and Kunal N. Chaudhury "Fast separable nonlocal means," Journal of Electronic Imaging 25(2), 023026 (25 April 2016). https://doi.org/10.1117/1.JEI.25.2.023026

Published: 25 April 2016

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