Séminaire d’Ambuj Mehrish, Post-Doctorant au LIUM
Estimation and Concealment of Forensic Multimedia Signatures
The remarkable evolution of digital imaging techniques, processing, and sharing in the past decades has spurred the penetration of multimedia into our lives. The unaccountable and ubiquitous use of multimedia brings severe issues and challenges about its origin and veracity. For instance, due to the growth of social media and instant messaging applications, the circulation of tampered content has become an unavoidable reality. The waning credibility of digital content has also led to unfavorable consequences in terms of political, economic, and social issues. Therefore, to address the source of origin and processing history-related issues of multimedia content, the scientific community has focused its attention on digital multimedia forensics techniques. On the other hand, to counter forensics algorithms, a parallel area of adversarial signal processing has also gained a lot of momentum. These counter-forensics algorithms are designed to hide the fingerprints left behind by image processing operations, thereby degrading the performance of forensics detectors. As a result, we are rapidly reaching towards a situation where one can no longer take the authenticity and integrity of digital images for granted. Therefore, this work focuses on digital forensics techniques capable of detecting several standard digital multimedia manipulations. In our first contribution, we address the problem of establishing the link between a given image to its source camera device. This problem is called Source Camera Identification. We also analyze the counter forensic algorithm for Contrast Enhancement, which is a common post-processing step in image tampering.