Gradient based illumination description for image forgery detection

This document describes a new physics-based method for image forensics called gradient-based illumination description. The goal is to determine the authenticity and origin of an image without an embedded security scheme. The key idea is that integrating over the gradient field of an object in an image indicates the direction of incident light, providing a descriptor that is robust to changes in object color or user input. This method operates on the whole object area rather than just contours. It is also unaffected by image resizing or compression, allowing analysis of images that current statistical methods cannot analyze.