Patent ID: 8374388

Claim:
A method for tracking the image position of a tracked object that appears in a plurality of successive frames of an image sequence, said method comprising the following steps: a) initializing the method by identifying a target region in one frame of said image sequence, wherein said target region contains pixels which represent an object which a user of this method wishes to track, b) developing a characterization of the tracked object by developing a characterization of those pixels which lie inside said target region, c) defining a search window, said search window comprising a designated region of the image which is to be searched for the tracked object, said search window to have an area r times greater than the area estimated for the target region identified in step a), said parameter r being a number that said user of the method must choose according to the kind of object being tracked, d) centering said search window on the centroid of the target region identified in step a), e) positioning the search window at an initial location in a successive frame of the image sequence, f) developing a characterization of said search window's pixels at said search windows present location in the present image in the sequence, g) computing, for each pixel in the search window, the probability that the said pixel represents the tracked object, said computation making use of numerical image data associated with said pixel, said characterization of said tracked object pixels developed in step b), said characterization of said search window pixels developed in step f), and Bayes law, said pixel probabilities thereby forming a two dimensional distribution of the tracked object's location in the image, h) estimating the new object location as the centroid of said two dimensional distribution calculated in step g), i) repositioning said search window to be centered on said new object location as determined in step h), j) iteratively repeating steps f), g), h), i) until the position of said search window converges, said convergence meaning that the difference between the positions, calculated for said search window in step i) of two consecutive said iterations, falls below a threshold value, k) repeating the steps e), f), g), h), i) for each successive frame of said image sequence.