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The Scientific World Journal
Volume 2014, Article ID 364501, 9 pages
http://dx.doi.org/10.1155/2014/364501
Research Article

Exposing Image Forgery by Detecting Consistency of Shadow

1School of Computer Science and Software Engineering, Tianjin Polytechnic University, Tianjin 300387, China
2Department of Logistics Management, Nankai University, Tianjin 300071, China

Received 27 December 2013; Accepted 12 February 2014; Published 13 March 2014

Academic Editors: A. Fernández-Caballero and C.-J. Lu

Copyright © 2014 Yongzhen Ke et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We propose two tampered image detection methods based on consistency of shadow. The first method is based on texture consistency of shadow for the first kind of splicing image, in which the shadow as well as main body is copied and pasted from another image. The suspicious region including shadow and nonshadow is first selected. Then texture features of the shadow region and the nonshadow region are extracted. Last, correlation function is used to measure the similarity of the two texture features. By comparing the similarity, we can judge whether the image is tampered. Due to the failure in detecting the second kind of splicing image, in which main body, its shadow, and surrounding regions are copied and pasted from another image, another method based on strength of light source of shadows is proposed. The two suspicious shadow regions are first selected. Then an efficient method is used to estimate the strength of light source of shadow. Last, the similarity of strength of light source of two shadows is measured by correlation function. By combining the two methods, we can detect forged image with shadows. Experimental results demonstrate that the proposed methods are effective despite using simplified model compared with the existing methods.