This section describes the functions that calculate the optical flow using the pyramidal Lucas-Kanade algorithm [ Bou99].
The optical flow between two images is generally defined as an apparent motion of image brightness. Let I(x, y, t) be the image brightness that changes in time to provide an image sequence.
Optical flow coordinates
can
be found from so called optical flow constraint equation:
The Lucas-Kanade algorithm assumes that the group of adjacent pixels has the same velocity and founds the approximate solution of the above equation using the least square method.