Patent ID: 6590999
Filing Date: 2003-07-08
Classification: G06K,G06T

Abstract:
A method for real-time tracking of a target which appears in a plurality of successive image frames, comprising the following steps:a) Identifying a given target in a given frame of a sequence of frames, said given target having a center in said given frame at a location y0, b) Developing a characterization of the given target, c) Developing a characterization of a candidate target in a successive frame of the sequence of frames, the candidate target initially being centered at the location y0 in the successive frame, d) Computing a Bhattacharyya coefficient (&rgr;) as a measure of similarity between the given target centered at the location y0 in the given frame and the candidate target centered at the location y0 in the successive frame, using the given and candidate target characterizations, e) Deriving a new location y1 for the candidate target in the successive frame by computing a gradient vector which corresponds to a maximization of the Bhattacharyya coefficient in the area of y0, f) Re-computing the Bhattacharyya coefficient (&rgr;) as a measure of similarity between the given target centered at the location y0 in the given frame and the new candidate target centered at the new location y1 in the successive frame, g) Comparing the result of step d) with the result in step f), and when the result in step f) is less than the result in step d), determining a new location y1â€² along the line determined by y0 and y1, and then repeating step f), but where y1 is replaced with y1â€², until the result in step f) is equal or greater than the result in step d), and h) Determining if y1â€² is within a threshold value of y0, and if it is, then that y1â€² corresponds to the location of the best target candidate, and if y1â€² is not within a threshold value of y0, assigning y1â€² to y0 and repeating steps d) through g) until it is.