图像变换（图像抑噪）

x=imread(‘pout,tif');

[m,n]=size(x);

xnoised=imnoise(x,'speckle',0.01);

subplot(211);imshow(xnoised);

Y=dct2(xnoised);

I=zeros(m,n);

I(1:m/3,1:n/3)=1;

Ydct=Y.*I;

Y=uint8(idct2(Ydct));

subplot(212);imshow(Y);