1. A system for inputting operation system (OS) commands to a data processing device comprising: (a) a video camera capturing images of a viewing space; and (b) a processor configured to: i) detect a predetermined object in one or more images obtained by the camera using an object recognition algorithm not involving background information in an image; ii) extract one or more image analysis parameters of the object in the one or more images obtained by the camera; and iii) for each of one or more motion detection tests: (I) applying the motion detection test to image analysis parameters extracted during a recent time window; and (II) executing an operating system command associated with the motion detection test if the motion detection test succeeds.