detección de movimiento

clear all;
clc
I1=imread('detect1.bmp');
I2=imread('detect2.bmp')
[m,n]=size(I1)
for i=2:m-1
for j=2:n-1
if (I1(i,j)<80)
I1(i,j)=0;
else I1(i,j)=255;
end

end
end
[m,n]=size(I2)
for i=2:m-1
for j=2:n-1
if (I1(i,j)<80)
I1(i,j)=0;
else I2(i,j)=255;
end

end
end
imshow(abs(I2-I1));