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), every ROI having a size and location; determining an initial template of the initial frame based on the initial ROI and a specified size; 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; identifying a first region of the first frame based on the initial ROI; finding a first plurality of first metric values based on the first region and a cost function; determining a first location of a first ROI of the first frame based on the plurality of first metric values; determining a second plurality of putative ROIs for the first frame, each putative ROI having a different size and the first location; determining a second metric value for each of the putative ROIs; and selecting one of the putative ROIs as the first frame's first ROI based on the second metric values.