Exposing digital forgeries from 3-D lighting environments

When creating a photographic composite, it can be difficult to match lighting conditions. We describe a technique for measuring lighting conditions in an image, and describe its use in detecting photographic composites. Specifically, we describe how to approximate a 3-D lighting environment with a low-dimensional model and how to estimate the model´s parameters from a single image. Inconsistencies in the lighting model are then used as evidence of tampering.