An important research is done to exploit the characteristics of PTZ cameras. These cameras allow motorized cover a wide field of view. A classic application of these cameras is to image mosaicing. But they can also be used to track moving objects. In this paper, we present an original approach for performing the registration, adapted to the case of central projection and a background subtraction algorithms for these cameras. The background image is iteratively updated and only on the part "seen" by the camera. We have experimented different segmentation algorithms using our background modeling technique and this approach makes it possible object tracking in real time for PTZ cameras.