Abstract: A video surveillance system (10) comprises a camera (25), a personal computer (PC) (27) and a video monitor (29). Video processing software is provided on the hard disk drive of the PC (27). The software is arranged to perform a number of processing operations on video data received from the camera, the video data representing individual frames of captured video. In particular, the software is arranged to identify one or more foreground blobs in a current frame, to match the or each blob with an object identified in one or more previous frames, and to track the motion of the or each object as more frames are received. In order to maintain the identity of objects during an occlusion event, an appearance model is generated for blobs that are close to one another in terms of image position. Once occlusion takes place, the respective appearance models are used to segment the resulting group blob into regions which are classified as representing one or other of the merged objects.