Mean Filter on Image

clear all; close all; clc;
a = imread('test_pattern.tif');
a = im2double(a);
a = imnoise(a,'gaussian',0.1);
figure,imshow(a);
[m n o]=size(a);
si=2;
%for r=1:3
for i = 1:m
for j = 1:n
con=0; s1=0;
for k1 = i-si:i+si
for p1 = j-si:j+si
if ((k1>0 && p1 >0) && (k1<m && p1<n))
con = con+1;
s1=s1+a(k1,p1);
end
end
end
b1(i,j)=s1/con;
end
end
%end
figure,imshow(b1),title('After Mean Filtering');