humbralizacion - deteccion de esquina

clear all;
clc
I1=imread('im1.jpg');

[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
V=double(zeros(2,4));
i=1;
j=1;
for i=10:m-1
for j=10:n-1
if (I1(i,j)==255)
V(1,1)=i;
V(1,2)=j;

end

end
end
i=1;
j=1;
for i=m-1:2
for j=n-1:2
if (I1(i,j)==255)
V(2,1)=i;
V(2,2)=j;

end

end
end
i=1;
j=1;
for j=n-1:2
for i=m-1:2
if (I1(i,j)==255)
V(3,1)=i;
V(3,2)=j;

end

end
end
i=1;
j=1;
for j=2:n-1
for i=2:m-1
if (I1(i,j)==255)
V(4,1)=i;
V(4,2)=j;

end

end
end
imshow(I1);