In order to detect bodies, you would need some sort of detector that operated by detecting features of bodies and looking for clusters or connected components of these. This is not a trivial problem whatsoever. Using the detectors that ship with Open

基于矩形拟合的人体检测,一种新的思路，新的方法来检测人体-Based on the rectangular fitting of human detection, a new idea, a new method to detect the human body