Aspects of the present disclosure are directed to tracking authorized individuals, and identifying the presence of unauthorized individuals. As may be consistent with one more embodiments, respective cameras capture images of regions of a common premises, and a filter circuit detects the presence of individuals in the images, and filters the detected presence as follows. The location of one or more authorized users are tracked relative to the premises via location-based information indicative of each authorized user's location. Each detected individual's location is identified and compared to the tracked location of the at least one authorized user. The detected individual is identified as being an unauthorized individual in response to the comparison indicating that the identified location is not common to the tracked location.
