Abstract: A video camera surveillance system used to monitor areas, during times of inactivity, for threats to safety and security such as the presence of intruders or fire. The system detects the magnitude of the difference between a reference frame and a frame coming from a camera. The system then counts the number of frames in which the aforementioned difference is above a certain threshold, and uses that number to discriminate between nuisances and real threats to security. Once the presence of a threat to security is determined, the system activates a video cassette recorder in addition to generating an alarm. The system then turns off the recorder when the area returns to normal, thus conserving video tape.