图像去噪 小波去噪方向 大神求解答！

X=imread('autumn.tif');
subplot(251);
imshow(X);
title('原始图像');
I=im2bw(X,0.5);
subplot(252);
imshow(I);
title('二值图像');
II=double(I);
j=imnoise(II,'gaussian',0,0.02);
subplot(253);
imshow(j);
title('高斯噪声');
k=imnoise(II,'salt & pepper',0.02);
subplot(254);
imshow(k);
title('椒盐噪声');
init=3718025452;
rand('seed',init);
f1=II+18*(rand(size(II)));
f1=uint8(f1);
subplot(255);
imshow(f1,[]);
title('随机噪声');
[C,S]=wavedec2(j,2,'db8');%用小波函数db8对B进行尺度为23的分解
[thr,sorh,keepapp]=ddencmp('den','wv',j);
%keepapp允许保留近似系数，keepapp为1时系数不能阈值化
%小波软阈值去噪，den去噪，wv小波
[XC1,CXC,LXC,PERF0,PERFL75]=wdencmp('gbl',C,S,'db8',3,thr,sorh,keepapp);
XC1=uint8(XC1);
subplot(258);
imshow(XC1,[]);
title('小波去高斯噪声');
[C,S]=wavedec2(k,2,'db8');%用小波函数db8对B进行尺度为23的分解
[thr,sorh,keepapp]=ddencmp('den','wv',k);
%keepapp允许保留近似系数，keepapp为1时系数不能阈值化
%小波软阈值去噪，den去噪，wv小波
[XC2,CXC,LXC,PERF0,PERFL75]=wdencmp('gbl',C,S,'db8',3,thr,sorh,keepapp);
XC2=uint8(XC2);
subplot(259);imshow(XC2,[]);
title('小波去椒盐噪声');
[C,S]=wavedec2(f1,2,'db8');%用小波函数db8对B进行尺度为23的分解
[thr,sorh,keepapp]=ddencmp('den','wv',f1);
%keepapp允许保留近似系数，keepapp为1时系数不能阈值化
%小波软阈值去噪，den去噪，wv小波
[XC3,CXC,LXC,PERF0,PERFL75]=wdencmp('gbl',C,S,'db8',3,thr,sorh,keepapp);
XC3=uint8(XC3);
subplot(2,5,10);
imshow(XC3);
title('小波去随机噪声');
为什么出来的结果加入随机噪声失败！对应的去噪也是错的，肯定是没有将随机噪声加入，求大神看看有什么毛病？