Illumination Analysis in Physics-Based Image Forensics: A Joint Discussion of Illumination Direction and Color

Illumination direction and color are two physics-based forensic cues that are based on the same underlying model. In this work, we discuss these methods in the light of their joint physical model, with a particular focus on the limitations and a qualitative study of failure cases of these methods. Our goal is to provide directions for future research to further reduce the list of constraints that these methods require in order to work. We hope that this eventually broadens the applicability of physics-based methods, and to spread their main advantage, namely their stringent models for deviations of the expected image formation.