The aim of the present invention is to provide a cost effective solution for a man-machine interface without physical contact with the device to which a command should be given. This aim is achieved by a Man-machine interface method executed by an interactive device, comprising a display, an infra-red camera, an infra-red illumination system, this method executing the following steps : - capturing a first image by the camera with infra-red illumination - capturing a second image by the camera without infra-red illumination - Subtracting the two images to create a difference image - Creating a movement map using a high-pass filter to filter-out static part on a plurality of difference images - computing a barycentre of at least one region of the movement map, - Assigning at least one cursor based on the position of the barycentre movement, - Modifying information on the display based on the position of this cursor..