Increase of digital CCTVs makes it difficult to analyze record images

In Japan, many CCTVs (Closed Circuit Television) have been operational in many places such as convenience stores, apartment houses, monetary facilities, parking lots for bicycles, railway stations and at vending machines, which were installed by companies or individuals in a voluntary manner in order to prevent crimes (Figure 1). On August 19 2009, the Nihon Keizai Shimbun, that is one of the newspapers in Japan, reported that the diffusion rate of CCTV of Japan amounted to one third of that of Britain. In this context, even if a CCTV is not installed at the scene of a crime, investigating record of a CCTV around the scene of crime contributes to a criminal investigation. Because the record may includes the passing criminal and/or criminal's vehicle. The information is indispensable for a criminal investigation. Therefore we research on technique for retrieving information on the recorded image with a quick, correct and digital forensic method.