SNN filter

Symmetric nearest neighbor edge-preserving filter.

This function implements the symmetric nearest neighbor filter, a 2D nonlinear filter that reduces noise in an image while at the same time preserving edge content. A code example follows:

RGB = imread('saturn.png');
I = rgb2gray(RGB);
J = imnoise(I,'gaussian',0,0.005);
Y = snn(J,5,true);