THESE/codes/nlmeans/demo.m

   1 clear\r
   2 clc\r
   3 clf\r
   4 colormap(gray)\r
   5 \r
   6 % create example image\r
   7 ima=100*ones(100);\r
   8 ima(50:100,:)=50;\r
   9 ima(:,50:100)=2*ima(:,50:100);\r
  10 fs=fspecial('average');\r
  11 ima=imfilter(ima,fs,'symmetric');\r
  12 \r
  13 % add some noise\r
  14 sigma=10;\r
  15 rima=ima+sigma*randn(size(ima));\r
  16 \r
  17 % show it\r
  18 imagesc(rima)\r
  19 drawnow\r
  20 \r
  21 % denoise it\r
  22 fima=NLmeansfilter(ima,5,2,sigma);\r
  23 \r
  24 % show results\r
  25 clf\r
  26 subplot(2,2,1),imagesc(ima),title('original');\r
  27 subplot(2,2,2),imagesc(rima),title('noisy');\r
  28 subplot(2,2,3),imagesc(fima),title('filtered');\r
  29 subplot(2,2,4),imagesc(rima-fima),title('residuals');\r
  30 \r