A Robust Digital Watermarking for Medical Images Based on PHTs-DCT

In recent years, digital watermarking technology has been widely used to solve the protection of privacy issues in medical images. However, the existing algorithms are failed to solve the protection problems against geometric attacks. To solve this problem, a robust digital watermarking algorithm for medical images based on PHTs-DCT is proposed in this paper. For embedding watermark, DCT is applied to reduce the redundant data of the image, then the coefficients are calculated via PHTs and the DCT to construct a binary feature sequence. Moreover, the watermark information is encrypted by Logistic mapping, and the zero watermark is constructed and stored in a third party medical image protection database. Extensive experiments have shown that the proposed algorithm has good robustness to geometric attacks and common attacks, especially anti-translation, rotation, and compression attacks.