Self-adaptive semi-fragile digital watermarking algorithm
具有自适应性的半脆弱数字水印算法*

In order to solve the contradiction between robustness and vulnerability of digital watermarking algorithm, this paper proposes a new self-adaptive semi-fragile digital watermarking method, with emphasis on digital watermarking embedding algorithm. By using improved low-pass filter, this algorithm adjusts gray value of middle pixel and changes gray-value differential of two terminal to embed the digital watermark. The experimental results show that this algorithm has strong robustness on all JPEG compression of Photoshop and has vulnerability for all geometric transformation malicious attacks. And from the extracted watermark, it can judge the characteristics of malicious attacks, such as types, extent and region. This algorithm shows good adaptability.