Abstract: An alert system includes a display device, a display control unit, and a target recognition unit. The display control unit: when the number of targets recognized by the target recognition unit is equal to or more than an upper limit number, sets a display range of a surrounding icon as a whole circular area; and in a state where the number of targets is equal to or more than the upper limit number and the display range of the surrounding icon is set as the whole circular area, when the number of targets increases, reduces the size of the surrounding icon.

Abstract: A fire detection system extracts fire (flame) portions from images produced by a monitoring camera while eliminating portions depicting artificial light sources. Portions depicting a light source that emits light are extracted from images produced by the monitoring camera. The system judges whether or not pairs of the extracted portions of images produced with the passage of time have a relationship of correspondence. If the extracted portions are contained in images produced for a given period of time, the light source is judged not to be the lamps of a moving vehicle, and is therefore identified as a fire. An area of an overlapping part of the extracted portions of images produced at different time instants, and an overall area of the extracted portions are computed, and the ratio of the area of the overlapping part to the overall area, that is, the area ratio between the extracted portions is computed. Incorrect alarming due to a vehicle at a standstill or a rotating lamp can be prevented.