A New Curvelet Based Blind Semi-fragile Watermarking Scheme for Authentication and Tamper Detection of Digital Images

摘要

A novel blind semi-fragile watermarking scheme for authentication and tamper detection of digital images is proposed in this paper. This watermarking scheme is based on Discrete Curvelet Transform (DCLT), which captures the information content of the image in few coefficients compared to other transforms. The novelty of the approach is that the first level coarse DCLT coefficients of the input image are quantized into 4 bits which is used as watermark and embedded into the pseudo randomly determined coefficients. At the receiver side, the extracted and generated first level coarse DCLT coefficients of the watermarked image are divided into blocks of uniform size. The difference in the energy between each block of extracted and generated coefficients is compared and if the difference exceeds threshold, the block is marked as tampered. This scheme exhibits higher Normalization Correlation Coefficient (NCC) values for various incidental attacks and is thus more robust than existing scheme [1]. The proposed scheme outperforms in localizing tampered regions compared to method [1].