1. A method, comprising: dividing a first frame of image data into a plurality of segments; calculating, with a processor, first fluctuation factors for respective ones of the segments, the first fluctuation factors respectively representative of changes in the respective segments from a second frame of image data to the first frame of image data; calculating, with the processor, a second fluctuation factor for the first frame; before performing object detection on the first frame: identifying ones of the plurality of segments of the first frame having a first fluctuation factor greater than the second fluctuation factor as active segments for the first frame; and linking, with the processor, adjacent ones of the active segments of the first frame to form a region of interest in the first frame; and performing, with the processor, the object detection on the region of interest.