Photographic Composite Detection Using Two Circles

Image forgery technology has become popular for tempering with digital photos. In this work, we propose a new technique for detecting the photographic composites using two or more equal and coplanar circles. In particular, we describe how to (i) estimate the focal length based on the equality of the sizes of two coplanar circles, (ii) estimate the normal vector of the world circle plane on the basis of the estimated focal length. Inconsistencies in the angles among the normal vectors (each circle determines a normal vector) are used as evidence of tampering. To demonstrate the efficiency of the approach, we test our method on both synthetic and visually plausible composite images.