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Non-local means filter --> Image denoise

There are several denoise filters such as Gaussian, bilateral and so on[1]. However, they may deteriorate the image quality. Non-local means filter is a powerful (but time-consuming >"<) denoise filter, which can preserve the detail of the image by averaging neighbor pixels with similar neighborhoods!

 The Matlab code can be found from the website listed in ref 2.
For more detail refer to ref 3.

 Example:

[1] https://web.cs.hacettepe.edu.tr/~erkut/bil717.s12/w09-bilateral-nlmeans.pdf
[2] https://pastebin.com/28GsvWkW
[3] https://www.youtube.com/watch?v=9tUns4HYtcw

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