A semi-fragile watermarking algorithm using adaptive Least Significant Bit substitution

A novel semi-fragile watermarking scheme in image spatial domain is proposed. Each watermark bit is duplicated and embedded into sub-blocks of the host image by adaptive Least Significant Bit (LSB) substitution. The adaptive LSB substitution fully exploits the Human Visual System (HVS) masking characteristics, which ensures high visual quality of watermarked image. The watermark for authentication is extracted by taking a majority vote on the extracted bits. To differentiate attack types effectively, a classification rule for image authentication was developed. Experimental results show that the proposed scheme has good transparency and robustness against admissible signal operations, while it is sensitive to malicious attacks such as heavy noise addition, rotation by large angle, cutting and pasting. In addition, the scheme can localize the tampered region precisely. © 2010 Asian Network for Scientific Information.