1. A data processing method comprising the steps of processing a first sample set associated with first results of tracking a target in a number of image frames using a first object classifier arranged to operate according to a first feature and processing a second sample set associated with second results of tracking the target in said number of image frames using a second object classifier arrange to operate according to a second feature, and using at least one of the first and second tracking results to influence at least one particle filter adapted to influence at least one of subsequent first and second tracking results.