Research On Privacy Protection Method For Medical Images Based On Lossless Digital Watermarking

Advanced digital technology has brought great convenience to information sharing and exchange of medical images between hospitals. The digital feature of medical images makes them very easy to storage and transmission, but it is also very easy to be intercepted or tampered with when the private medical information was transmitted through public network. Therefore, how to protect privacy information of medical images has become an urgent problem to be solved at present.Because of reversibility of lossless digital watermarking technology, it is widely used in high image accuracy requirements, such as medicine, remote sensing, and military scene. Lossless invisible digital watermarking can hide invisible private information in medical images, which protects the private information of medical images in a passive manner. Nevertheless, the lossless visible digital watermark can cover lesions in medical images with visible watermarks, which protects the private information of medical images in a active way. Both of them can lossless recover the original image at the receiving end.The main work and contributions of this paper are as follows:1) A more comprehensive overview about medical images Lossless digital watermarking technology was given;2) Due to the characteristics of high quality, high capacity, authentication, frequent modification of privacy information and reversibility of the medical images lossless digital watermarking, a lossless invisible digital watermarking scheme for medical images based on prediction error modification is proposed. The proposed method uses a non-block-based approach and acquires prediction images by using a weighted linear predictor. In the prediction error histogram, it takes the advantage of four peak points to embed the private data, and the method solves the overflow problem well which appears in medical images by using the method of edge pixels shifting. It increases the embedding capacity while keeping the distortion.3) This paper proposes a lossless visible digital watermarking scheme for medical images based on Human Visual System which is used for better covering the lesion area of medical images via Human Visual System. The proposed method uses a contraction projection technology which means projecting the pixel to one of the areas, flow challenge in medical images has been worked out and decreased the hidden additional information by strictly controlled flow issues. Secret key enhances the robustness of watermarking, and the visible watermarking cannot be removed without the right secret key. The adjustable intensity of watermark strengthens the flexibility of visible watermark. Self-adaptive visible watermark achieves a good balance between visibility and transparency. It achieves a good effect in medical image.