1. A method, comprising: generating, with a random number generator, a random subset of pixels of a first frame, the random subset of pixels including less than all of the pixels of the first frame; generating, via a processor, a first fluctuation factor for the first frame by averaging fluctuation values of the random subset of pixels of the first frame; identifying, via the processor, a person indication area in which a person is believed to be located, the person indication area corresponding to a subset of the pixels of the first frame including less than all of the pixels of the first frame; generating, via the processor, a second fluctuation factor for the person indication area of the first frame by averaging fluctuation values of the subset of the pixels corresponding to the person indication area; and marking, via the processor, the person indication area as corresponding to a false positive when the second fluctuation factor is less than or equal to the first fluctuation factor.