Aluno: Victor Chitolina Schetinger
Orientador: Prof. Dr. Manuel Menezes de Oliveira Neto
Title: Digital Image Forensics Beyond Digital, Images, and Forensics: Towards a Regulation of Trust in Multimedia Communication
Linha de Pesquisa: Computação Gráfica, Processamento de Imagens e Interação
Local: Prédio 43412 – Sala 215 (sala de videoconferência), Instituto de Informática
Prof. Dr. Anderson de Rezende Rocha (UNICAMP – por videoconferência)
Prof. Dr. William Robson Schwartz (UFMG)
Prof. Dr. Luis da Cunha Lamb (UFRGS)
Presidente da Banca: Prof. Dr. Manuel Menezes de Oliveira Neto
Abstract: This thesis discusses the role of Digital Image Forensics as a regulator of digital media in society. This includes a perceptual study with over 400 subjects to assess their ability to notice editing in images. The results of such experiment indicate that humans are easily fooled by digital images, not being able to tell apart edited and pristine images. The thesis then analyzes the effectiveness of the available arsenal of digital image forensics technology to detect image editing performed by state-of-the-art image-compositing techniques. By analyzing fundamental image patterns, forensics techniques can effectively detect the occurrence of most types of image compositing operations. In response to these two studies, the thesis presents an alternative approach to digital image forensics, based on automated plan generation. By treating the image inspection process as a plan comprised of different steps, it proposes an architecture that is able to guide an analyst choosing the next best step for inspecting an image. The generated plans are flexible, adapting on the fly to the observed results. The plans are based on a formal modelling of current forensics knowledge and techniques, so that they can be translated in steps to be executed. The thesis then shows that the limits of such an approach lie in the difficulty to validate results, which is a consequence of the setup of forensics problems: they are problems of distributed trust among parties with limited information. This scenario is analyzed from different perspectives in search for the practical limits of Digital Image Forensics as a whole. The results of such an analysis suggest that the field is lacking in providing practical and accessible solutions to society due to limited engagement in multidisciplinary research rather than due to limited technical proficiency. The thesis then discusses how paradoxes from philosophy, mathematics, and epistemology arise naturally in both real forensics scenarios, and in the theoretical foundations of the field. Digital Image Forensics ultimately deals with human communication and, as such, it is subject to all its complexities. Finally, it is argued that the path for providing useful solutions for society requires a collective engagement from different disciplines. It is the responsibility of the forensics community to develop a common, accessible epistemological framework for this collective enterprise.
Keywords: Digital Image Forensics, Image Compositing, Planner.