1. In an object detection system having at least one processor circuit configured to receive a series of image regions and apply to each image region in the series a detector, the detector configured to determine a presence of a predetermined object in the image region, a computer implemented method of selecting and applying the detector, the method comprising: selecting and applying, by the at least one processor circuit, the detector from among a plurality of foreground detectors and a plurality of background detectors in a repeated pattern comprising: sequentially selecting, by the at least one processor circuit, a selected one of the plurality of foreground detectors; sequentially applying, by the at least one processor circuit, the selected one of the plurality of foreground detectors to one of the series of image regions until all of the plurality of foreground detectors have been applied; selecting, by the at least one processor circuit, a selected one of the plurality of background detectors; and applying, by the at least one processor circuit, the selected one of the plurality of background detectors to one of the series of image regions.