A novel watermarking algorithm in DCT domain to authenticate image content

This paper proposes a novel watermarking algorithm based on block DCT transform to authenticate image content. The original image is subdivided into 8×8 blocks and each block is transformed to DCT domain, then a special mark derived from certain low frequency coefficients is hided into the middle frequency DCT coefficients of another pseudo-randomly selected block. Watermark detecting is based on the correlation calculation between the low frequency coefficients and the corresponding middle frequency coefficients. Experiment shows that the algorithm is robust to JPEG compression, and it can be used to detect image content tamper. The algorithm has low rate of false detection and failure detection and it is safe to be used in image content authentication.