Improving Capability of Locating Tampered Pixels of Statistical Fragile Watermarking

Abstract

A fragile watermarking scheme proposed by Zhang and Wang introduces a statistical mechanism and can accurately localize the pixels with at least one of the 5 most significant bits (MSBs) altered. However, localization of tampered 3 least significant bits (LSBs) is considered unnecessary because these bits are replaced by watermark bits. If the tampered 3 LSBs can be also localized, the pattern of tampering will be identified more correctly. This paper proposes a bit-wise scheme to localize tampered 3 LSBs using information on the tampered 5 MSBs in the statistical scheme. Experimental results show that the proposed scheme can accurately localize tampered 3 LSBs and that the combination of the previous scheme and the proposed one contributes to more exact identification of the tampering pattern. In this sense, we improve the capability of the statistical scheme.KeywordsImage authenticationfragile watermarkingtampered-MSB localizationtampered-LSB localization