对图像的腐蚀与膨胀

clc;
close all;
img=imread('baihe.jpg');
img_gray=rgb2gray(img);
subplot(221),imshow(img_gray);
[m n]=size(img_gray);
img_gray_fu=zeros(m,n);
img_gray_peng=zeros(m,n);
for i=2:m-1
    for j=2:n-1
        img_gray_fu(i,j)=min(min(img_gray(i-1:i+1,j-1:j+1)));
        img_gray_peng(i,j)=max(max(img_gray(i-1:i+1,j-1:j+1)));
    end
end
subplot(222),imshow(uint8(img_gray_fu));

subplot(223),imshow(uint8(img_gray_peng));