Sensor Defects in Digital Image Forensic

Just as human fingerprints or skin blemishes can be used for forensic purposes, imperfections of digital imaging sensors can serve as unique identifiers in numerous forensic applications, such as matching an image to a specific camera, revealing malicious image manipulation and processing, and determining an approximate age of a digital photograph. There exist several different types of defects that are of interest to the forensic analyst caused by imperfections in manufacturing, physical processes occurring inside the camera, and by environmental factors. This chapter begins with analyzing pixel defects, while pointing out their forensic potential. Then, specific problems are formulated as tasks involving detection or matching of defects and noise patterns. Practical algorithms for these tasks are developed within the framework of parameter estimation and signal detection theory. The performance of the algorithms is demonstrated on real-world examples.