Patent ID: 7425981

Claim:
A method of setting a region of interest in each of a sequence of video frames, each video frame comprising a plurality of pixel values, the method including, in respect of each video frame following a predetermined number of initial frames: generating in respect of each video frame an instantaneous region of interest; determining whether, and if so to what extent, to modify the region of interest set for the preceding video frame, in order to determine the region of interest for the currently considered video frame, according to a stepped procedure; and setting the region of interest of the currently considered video frame in accordance with the result of the determination performed according to the stepped procedure; wherein the stepped procedure includes: (a) comparing a first boundary defining the instantaneous region of interest of the currently considered frame, or sections thereof, with a second boundary defining the region of interest set for the preceding frame, or corresponding sections thereof, and (b) if the difference is greater than a threshold amount, modifying the second boundary, or sections thereof, in the direction towards the first boundary, or the corresponding sections thereof, by an amount which is constrained to be equal to or below a maximum step amount.