%裝載并顯示原始圖象
load flujet;
subplot(2,2,1);
image(X);
colormap(map);
title('原始圖象');
axis square;
%=============================================
%加噪并顯示圖象
init=2055615866;
rand('seed',init);
XX=X+25*randn(size(X));
subplot(2,2,2);
image(XX);
colormap(map);
title('含噪圖象');
axis square;
%===============================================
%對圖象消噪
%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);
%==============================================
%顯示消噪后的結果
subplot(2,2,3);
image(a1);
colormap(map);
title('第一次消噪圖象');
axis square;
subplot(2,2,4);
image(a2);
colormap(map);
title('第二次消噪圖象');
axis square;