I= imread('E:\matlab\work\1.png');     %读取图片
i=im2double(I);
J=imread('E:\matlab\work\2.png');
j=im2double(J);
p=i-j;
P=p*255;
imshow(P,[]);

</pre><pre name="code" class="plain">j=zeros(366,572);
i=imread('E:\matlab\work\cancer.bmp');
i=double(i);
a=0;b=0;
for m=1:365
   for n=1:571
      a=i(m,n)-i(m+1,n);
      b=i(m,n)-i(m,n+1);
      a=abs(a);b=abs(b);
      if a>b
         j(m,n)=a;
      else
         j(m,n)=b;
      end
      if j(m,n)>3
         j(m,n)=0;
      else
         j(m,n)=255;
      end
   end
end
imshow(j,[0 255]);