A Robust Zero Watermarking Algorithm for Medical Images Based on Tetrolet-DCT.

The rapid development of the information age of big data has promoted the development of traditional medicine and online diagnosis, as well as aroused concerns about the privacy of patient information. Aiming at the hidden dangers of copying, cutting, tampering, etc. in the dissemination of medical images, combined with the characteristics of medical images, this paper proposed a novel zero-watermarking algorithm based on Tetrolet-DCT, focusing on how to improve its security. Logistic map chaotic encryption is performed on the watermark, the Tetrolet-DCT transform is used to extract the visual feature of medical image, and the watermark information is embedded and extracted by combining the zero-watermarking technology. Experimental data show that the algorithm proposed in this paper can effectively extract the watermark without any changing of the medical image, and has a higher NC value under conventional attacks and geometric attacks. it has better invisibility and robustness.