Hannes Mareen
IDLab‑MEDIA, Ghent University – imec, Belgium
How AI-Based Regeneration Reshapes Multimedia Forensics
Abstract. Diffusion models are widely known for generating new images from text, but their capabilities extend much further, into restoration, enhancement, editing, and compression. These AI tools unlock impressive creative and technical possibilities, but also blur the line between real and synthetic content, posing new challenges for multimedia forensics. First, AI-based compression may appear content-preserving, yet it can subtly alter image semantics. This poses serious risks, for instance, when analyzing sensitive material such as surveillance footage. Moreover, such processing can introduce artifacts resembling those of generative models, meaning authentic media might be incorrectly flagged as synthetic. Even more disruptive, diffusion-based regeneration can erase forensic traces used for watermarking, deepfake detection, or image forgery localization. This can occur intentionally in targeted attacks or unintentionally through image processing such as super-resolution. Finally, current image forgery localization methods fail to localize edits performed by new AI-based inpainting methods because they fully regenerate the edited images. As AI-based regeneration becomes embedded in everyday media workflows, multimedia forensics must evolve to safeguard trust in visual evidence in the era of generative AI.
Biography. Hannes Mareen is a postdoctoral researcher at IDLab‑MEDIA, Ghent University – imec, Belgium. He completed his Bachelor’s, Master’s, and PhD in Computer Science Engineering at the same university in 2014, 2017, and 2021, respectively. Hannes specializes in multimedia forensics, security, compression, and other applications. Within forensics, he has contributed to work on (deep)fake image detection, perceptual hashing, video watermarking, and more. For example, he designed the COM-PRESS image manipulation analysis dashboard for fact‑checkers, the Comprint method for image forgery localization, and the TGIF dataset containing text-guided inpainted images. Beyond research, Hannes is active in science communication and has received several distinctions. For example, he received the best paper award at IEEE GEM 2024, he won the Agoria Prize 2017, two best poster awards, the #ThesisThread 2021 competition, and finished third in the Flemish PhD Cup 2022.
Kiran Raja
Synthetic Data for Biometric Attacks and Defenses
Abstract. This talk will present recent works in the directions in face recognition driven by synthetic data and modern generative models. It will highlight how GANs and diffusion models enable the creation of realistic facial images and ID card portraits for evaluating biometric vulnerabilities, including morphing attacks and identity manipulation without relying on sensitive personal data. These synthetic pipelines offer scalable and controlled environments for stress-testing recognition systems. We also discuss generative editing techniques that modify biometric cues within latent spaces to produce natural, identity-safe outputs, supporting privacy-preserving applications while maintaining utility for downstream tasks. The talk connects progress in synthetic data generation with methods for both strengthening biometric security and preserving individual privacy.
Biography. Kiran Raja is a Professor of Department of Computer Science at the Norwegian University of Science and Technology (NTNU), Norway. He obtained his PhD in Computer science from NTNU in 2016. He has participated in EU funded projects such as SOTAMD, iMARS, INGRESS and other nationally funded projects on biometrics, security and machine learning. During his participation in SOTAMD and iMARS projects at Norwegian Biometrics Laboratory (NBL), he has worked on different problems in morphing attacks from both generation and detection perspectives. He is a member of the European Association of Biometrics (EAB) and chairs the Academic Special Interest Group at EAB. He also advises various national agencies in Norway on making biometric systems secure. His recent research focuses on attacks and defenses on biometric systems using statistical pattern recognition, image processing, and machine learning.