A tour of nonlocal means techniques for image filtering

Vargas, José Ismael De la Rosa; Villa, Jesús; González, Efrén; Cortez, Joaquín

doi:10.1109/conielecomp.2016.7438548

Cited by 5 publications

(3 citation statements)

References 28 publications

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“…We note that, because of their adaptive processing properties, NLM methods recently have been used for noise suppression in many applications (Chan et al 2010, Chun et al 2012, Dutta et al 2013, Chun and Dewaraja 2013. For a detailed review, the interested readers are referred to (Buades et al 2005a, Wilson and Das 2013, de la Rosa Vargas et al 2016. In emission tomography, NLM filtering was applied to improve the resolution of SPECT images by incorporating anatomical information derived from computed tomography (CT) (Chun et al 2012, Chun andDewaraja 2013).…”

Section: Song Et Almentioning

confidence: 99%

“…In practice, these coefficients are designed such that those voxels that are more similar to voxel i will contribute more to the filter output at i, thereby achieving spatially adaptive processing according to the image content. Because of this, NLM filter is reported to have edge preserving properties (Buades et al 2005b, de la Rosa Vargas et al 2016.…”

Section: Spatial Nlm Filteringmentioning

confidence: 99%

“…We note that, because of their adaptive processing properties, NLM methods recently have been used for noise suppression in many applications [16–19]. For a detailed review, the interested readers are referred to [20–22]. In emission tomography, NLM filtering was applied to improve the resolution of SPECT images by incorporating anatomical information derived from computed tomography (CT) [18,19].…”

Section: Introductionmentioning

confidence: 99%

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4D non-local means post-filtering for cardiac gated SPECT

et al. 2018

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Cardiac gated images often suffer from increased noise in single photon emission computed tomography (SPECT) due to reduced data counts compared to non-gated studies. We investigate a spatiotemporal post-processing approach based on a non-local means (NLM) filter for suppressing the noise in gated SPECT images. In this filter, the output at a voxel location is computed from a weighted average of voxels in its four-dimensional (4D) neighborhood, wherein the filter coefficients are adjusted according to the similarity level in the local image pattern of individual voxels with respect to the output voxel. This adaptive property allows the filter to achieve noise reduction while avoiding excessive blur of the heart wall. In the experiments, we first evaluated the accuracy of the proposed NLM filtering approach using simulated SPECT imaging data. We then demonstrated the approach on eight sets of clinical acquisitions. In addition, we also explored the robustness of the NLM filter with imaging dose reduced by 50% in these clinical acquisitions. The quantitative results show that 4D NLM filtering could effectively reduce the noise level in gated images, leading to more accurate reconstruction of the myocardium. Compared to spatial filtering alone, using temporal filtering in NLM could reduce the mean-squared-error of the myocardium by 55.63% and improve the left ventricle resolution by 19.92%. It could also improve the visibility of perfusion defects in gated images. Similar results are also observed on the clinical acquisitions both at standard dose and at 50% reduced dose. The 4D NLM results are also found to be comparable to that of a motion-compensated 4D reconstruction approach which is computationally more demanding.

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