%裝載原始圖像
load sinsin;
subplot(2,2,1);image(X);colormap(map);title('含噪圖像');
%對圖像加噪聲并顯示出含噪圖像
init=2788605800;
randn('seed',init);
X=X+10*randn(size(X));
subplot(2,2,2);image(X);colormap(map);title('含噪圖像');
%應用中值濾波進行圖像平滑處理
[p,q]=size(X);
for i=2:p-1
    for j=2:q-1
        Xtemp=0;
        for m=1:3
            for n=1:3
                Xtemp=Xtemp+X(i+m-2,j+n-2);
            end
        end
        Xtemp=Xtemp/9;
        X1(i,j)=Xtemp;
    end
end
subplot(2,2,3);image(X1);colormap(map);
title('平滑濾波后圖像');
%應用小波變換進行消噪
wname = 'coif2'; lev = 3;
[c,s] = wavedec2(X,lev,wname);
det1 = detcoef2('compact',c,s,1);
sigma = median(abs(det1))/0.6745;
alpha = 1.2;
thr = wbmpen(c,s,sigma,alpha);
keepapp = 1;
xd = wdencmp('gbl',c,s,wname,lev,thr,'s',keepapp);
subplot(2,2,4); image(xd);colormap(map);title(' 小波消噪后圖像');