图像缩小2倍后，中值滤波，matlab程序

clear
I=imread('e:\gz\1\1.jpg');
J=rgb2gray(I);
[m n]=size(J)
M=zeros(0);
for i=1:2:n %图像缩小2倍
     for j=1:2:m
        k=J(j,i);
        M=[M;k];
     end
end
M=reshape(M,m/2,[]);
imshow(M)
figure;
imshow(J)
M=double(M);
[m n]=size(M);
for i=1:n-4 %中值滤波
      for j=1:m
        T=zeros(5,1);
        T(1)=M(j,i); %中值滤波模版
        T(2)=M(j,i+1);
        T(3)=M(j,i+2);
        T(4)=M(j,i+3);
        T(5)=M(j,i+4);
         for k=1:4
           if(T(k)>T(k+1))
             t=T(k);
             T(k)=T(k+1);
             T(k+1)=t;