1. A data processing method comprising: processing, in a system having a processor, 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; processing, in the system, 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; using, in the system, at least one of the first and second tracking results to influence at least one particle filter configured to influence at least one of subsequent first and second tracking results; generating, by the at least one particle filter, a new sample set of samples; computing sample weightings based on features of the samples in the new sample set; producing, based on the sample weightings, position information representing a coordinate of the target; and updating the first and second object classifiers using the position information.