Abstract: A simple tampered portrait identification algorithm based on inconsistent shadow was proposed by analyzing of binarization of the image shadow．The algorithm determines whether the image is tampered by first manually selecting the local image of the nose area and chin area,then statistically analyzing shaded area after Ostu binarization process,and finally comparing the shadow consistency between the nose area and chin area．A lot of experimental results show that the method has simplicity,high accuracy,strong reliability and has some practical value in image forensics．

Key words: Shadow,Binarization,Blind forensics