1. An object tracking method, comprising: receiving an initial frame from a temporal sequence of frames, the initial frame having an initial region-of-interest (ROI), the initial ROI having an initial location and an initial size; determining an initial histogram and an initial luminance measure based on the initial ROI; receiving a first frame from the temporal sequence of frames, the first frame arriving later in the temporal sequence of frames than the initial frame; determining a plurality of putative ROIs for the first frame, each putative ROI based on the initial histogram and the initial luminance measure; determining a plurality of quality metric values, each quality metric value corresponding to a different one of the putative ROIs; selecting one of the putative ROIs as a first ROI for the first frame based on the quality metric values; obtaining a first histogram and a first luminance measure based on the first ROI; receiving a next frame from the temporal sequence of frames, the next frame arriving later in the temporal sequence of frames than the first frame; and determining a next ROI of the next frame based on the first ROI, the first histogram, and the first luminance measure.