gusucode.com > matlab编程小波变换进行图像去噪处理，包括各种软硬阈值的选取函数 > code/Untitled3.m

    clear all
clc;
f=imread('graylena.bmp');
f=double(f);
s=size(f);
r=imnoise2('gaussian',s(1),s(2),0,20);%填加高斯白噪声
fnoisy=f+r;
%对图像进行三层小波分解
[c,s]=wavedec2(fnoisy,3,'db8');
cA3=appcoef2(c,s,'db8',3);
[cH3,cV3,cD3]=detcoef2('all',c,s,3);c3=[cH3,cV3,cD3];
[cH2,cV2,cD2]=detcoef2('all',c,s,2);c2=[cH2,cV2,cD2];
[cH1,cV1,cD1]=detcoef2('all',c,s,1);c1=[cH1,cV1,cD1];

%固定阈值（VisuShrink阈值）：thr=delta*sqrt(2*log(n));
delta=median(abs(cD1(:)))/0.6745;
thr1c=delta*thselect(c,'sqtwolog');

origif=cacupsnr(fnoisy,f)

dnc1=wthresfunc(c,s,'newthr1',thr1c);
dnf1=waverec2(dnc1,s,'db8');
figure,subplot(221),imshow(dnf1,[]),title('硬阈值函数')
VSf1=cacupsnr(dnf1,f)