![](https://csdnimg.cn/release/download_crawler_static/22687507/bg1.jpg)
% average filter
% filter 1
o_i=double(imread('fig57a.jpg'));
subplot(221);
imagesc(o_i);
colormap(gray);
title('原始图像')
o_i_n=double(imread('fig57b.jpg'));
subplot(222);
imagesc(o_i_n);
colormap(gray);
title('含噪图像')
[m,n]=size(o_i);
plate=zeros(3,3);
f=o_i_n;
for i=2:m-1
for j=2:n-1
plate=o_i_n(i-1:i+1,j-1:j+1);
f(i,j)=sum(sum(plate))/9;
end
end
subplot(223);
imagesc(f);
colormap(gray);
title('算术平均')
%filter 2
[m,n]=size(o_i);
plate=zeros(3,3);
f=o_i_n;
for i=2:m-1
for j=2:n-1
plate=o_i_n(i-1:i+1,j-1:j+1);