Identifying Image Composites Through Shadow Matte Consistency

In this paper, we propose a framework for detecting tampered digital images based on photometric consistency of illumination in shadows. In particular, we formulate color characteristics of shadows measured by the shadow matte value. The shadow boundaries and the penumbra shadow region in an image are first extracted. Then a simple and efficient method is used to estimate shadow matte values of shadows. Our approach efficiently extracts these constraints from a single view of a target scene and makes use of them for the digital forgery detection. Experimental results on both simulated photos and visually plausible real images demonstrate the effectiveness of the proposed method.