Image authentication and tamper detection using two complementary watermarks

This paper presents a novel semi-fragile watermarking scheme for image authentication and tamper detection. The proposed scheme extracts content-based image features from the approximation subband in the wavelet domain to generate two complementary watermarks. Specifically, we generate an edge-based watermark sequence to detect any changes after manipulations. This edge-based watermark encodes the invariant relationship between quantized wavelet coefficients after incidental distortions. We also generate the content-based watermark to localize tampered regions. Both watermarks are embedded into the high frequency wavelet domain to ensure the watermark invisibility. Our extensive experimental results show that the proposed scheme outperforms the peer scheme and can successfully identify intentional tampering and incidental modification, and localize maliciously tampered regions.