close all
clear
clc
disp('====E4_7_1.m====');

I=[0   20  40  70
   80  100 120 150
   160 180 200 230]
uint8I=uint8(I)
subplot(2,2,1),imshow(uint8I),ylabel('原始图像');
subplot(2,2,2),imhist(uint8I);

mask = fspecial('average',5)    % 语句1
J=filter2(mask,uint8I)
uint8J=uint8(J)
subplot(2,2,3),imshow(uint8J),ylabel('3*3均值滤波后的图像');
subplot(2,2,4),imhist(uint8J);