A method is provided for detecting a body part in a video stream from a mobile device. A video stream of a human subject is received from a camera connected to the mobile device. The video stream has frames. A first frame of the video stream is identified for processing. This first frame is then partitioned into observation windows, each observation window having pixels. In each observation window, non-skin-toned pixels are eliminated; and the remaining pixels are compared to determine a degree of entropy of the pixels in the observation window. In any observation window having a degree of entropy above a predetermined threshold, a bounded area is made around the region of high entropy pixels. The consistency of the entropy is analyzed in the bounded area. If the bounded area has inconsistently high entropy, a body part is determined to be detected at that bounded area.