Photo Forensics From Rounding Artifacts

Many aspects of JPEG compression have been successfully used in the domain of photo forensics. Adding to this literature, we describe a JPEG artifact that can arise depending upon seemingly innocuous implementation details in a JPEG encoder. We describe the nature of these artifacts and show how a generic JPEG encoder can be configured to explain a wide range of these artifacts found in real-world cameras. We also describe an algorithm to simultaneously estimate the nature of these artifacts and localize inconsistencies that can arise from a wide range of image manipulations.