1. A method of detecting a body part in a video stream from a mobile device, comprising: (a) receiving a video stream of a human subject from a camera connected to the mobile device, the video stream having frames; (b) identifying a first frame of the video stream for processing; (c) partitioning the first frame into observation windows, each observation window having pixels; (d) in each observation window: (i) eliminating non-skin-toned pixels; and (ii) comparing the remaining pixels to determine a degree of entropy of the pixels in the observation window; (e) in any observation window having a degree of entropy above a predetermined threshold, making a bounded area around the region of high entropy pixels; and (f) analyzing the consistency of the entropy in the bounded area, wherein if the bounded area has an inconsistently high entropy, a body part is determined to be detected at the bounded area.