Let’s look at an example of this. Suppose we have an image with a corner.
1111111111
-----------------
1222222222 And this
translates down and to the right: -1111111111
1233333333
-1222222222
1234444444
-1233333333
Let’s compute It for the whole second image:
---------- Ix
= ---------- Iy = -------------
0-1-1-1-1-1
--00000
--------------
-1-1-1-1-1-1
--.50000
-0-.5-1-1-1-1-1-1
-1-1-1-1-1-1-
--1.5000
-00-.5-1-1-1-1-1
Then the equations we get have the form:
(.5,-.5)*(u,v) = 1,
(1,0)*(u,v) = 1, (0,-1)(u,v) =
1.
Together, these lead to a solution that u = 1, v = -1.