1. A method for selectively tracking an object appearing in a video sequence comprising a plurality of frames, each frame comprising a plurality of pixels, the method comprising: (a) identifying a first object in a first frame and associating therewith a first status parameter indicative of a non-tracking condition; (b) identifying a plurality of candidate objects in a subsequent frame and determining whether there is a correspondence between any one of the candidate objects and the first object; (c) in the event of correspondence between a candidate object and the first object, repeating step (b) for that candidate object over subsequent frames until a predetermined number of sequential correspondences are identified; (d) changing the first status parameter to a second status parameter when said predetermined number of sequential correspondences are identified; and (e) in response to the change from first to second status parameter, recording the intra-frame position of said object for subsequent frames; wherein correspondence is determined in step (b) by: calculating a first similarity score between each candidate object and the first object using a first cost function, calculating a second similarity score using a second cost function which is different from the first cost function, grouping the calculated similarity scores in accordance with the status parameter of the first object, analyzing each group in a predetermined order and selecting the closest match between the candidate objects and the first object.