1. A method for determining whether a gesture is being performed in a sequence of source images, the method comprising: detecting the gesture in each of one or more reference images using one or more gesture models of a plurality of gesture models; selecting a first gesture model from the one or more gesture models that most closely matches the detected gesture; prioritizing the first gesture model over other gesture models in the plurality of gesture models for searching for the gesture in the sequence of source images; scanning the sequence of source images to determine whether the gesture is being performed, using the prioritized first gesture model; and if the gesture is being performed, ending scanning prior to using another gesture model of the plurality of gesture models to determine whether the gesture is being performed.