A self-embedded watermarking scheme based on relationship function of corresponding inter-blocks DCT coefficient

In the realm of computer supported cooperative work in design (CSCWD), how to ensure the authenticity and integrity of an image plays important roles. This paper presents a novel semi-fragile image watermarking scheme for authenticating and recovering image content. The scheme also shows strong robustness on those images' content reserved operations. It can precisely detect and locate malicious operations and tampers, and recover main content of tampered image region. Firstly, it assigns the exclusive precursor block and successor block for every block to be a block circle link, and regards the function mapping result of DCT coefficients of neighboring blocks as watermark, and embeds it into middle-frequency domain of DCT coefficients of successor block to form a watermarked image. Secondly, it verifies the blocks, which have been maliciously operated and tampered, by detecting whether the DCT coefficients of neighboring blocks satisfy the relationship function after operations. Thirdly, it uses corresponding relationship function of neighboring blocks in the link to estimate DCT direct current coefficients (DC) and low-frequency coefficients of the tampered blocks and recovers their main content. The experimental results show that the scheme is effective and feasible.