1. Field of the Invention
The present invention relates to an image search apparatus applied to a surveillance camera system. More specifically, the present invention relates to an image search apparatus for searching a desired image from among a plurality of images recorded on a recording medium.
2. Description of the Prior Art
In a conventional such a kind of surveillance camera system, an arbitrary area of a surveillance image (live image) is set as an surveillance area, and a chronological change of a luminance level at the surveillance area is determined. An alarm is generated at a time an amount of the change between frames exceeds a threshold value. Furthermore, the surveillance image is recorded on an image recording apparatus such as a hard disk recorder or a VCR (Video Cassette Recorder) so as to be confirmed after that.
However, in the prior art, when searching for the surveillance image at a time the alarm was generated from among a plurality frames of the surveillance images recorded, there is a need to confirm each frame of surveillance image by the naked eye (i.e. manually), and therefore, it is too much troublesome.
Furthermore, even if there occurs a suspicious movement at an area other than the surveillance area, and there occurs a significant change in the luminance level, the alarm is not generated. It is more troublesome and difficult to search for an image in which the suspicious movement occurs from among the images in which the alarm is not generated. In addition, in a prior art, since the alarm is generated at a time an amount of change in the luminance level between the adjacent two frames exceeds the threshold value, no alarm might be generated in a case the luminance level of the surveillance image gradually changes. Thereupon, there is an occasion that the suspicious movement occurring in the surveillance area may be missed out in reproducing.