%裝載原始圖像信號并圖示
load wgatlin;
subplot(2,2,1);
image(X);
colormap(map);
title('原始圖像');
axis square;
%==============================
%生成含噪圖像并圖示
init=2055615866;
rand('seed',init);
XX=X+12*randn(size(X));
subplot(2,2,2);
image(XX);
colormap(map);
title('含噪圖像');
axis square;
%==============================
%下面對圖像消噪
%首先用sym4小波函數對XX進行2層分解
[c,l]=wavedec2(XX,2,'sym4');
%實現低通濾波消噪
a1=wrcoef2('a',c,l,'sym4',1);
%再次實現低通濾波消噪
a2=wrcoef2('a',c,l,'sym4',2);
%==============================
%圖示消噪處理后的結果
subplot(2,2,3);
image(a1);
colormap(map);
title('第一次消噪圖像');
axis square;
subplot(2,2,4);
image(a2);
colormap(map);
title('第二次消噪圖像');
axis square;