A new multi watermarking algorithm for medical images using DWT and hash functions

In this paper, we propose a blind digital multi- watermarking algorithm for the copyright protection and authentication of medical images. When medical images are transmitted and stored in hospitals, strict security, confidentiality and integrity are required to protect from the illegal distortion and reproduction of the medical information. Medical image watermarking requires extreme care when embedding watermark information in the medical images because the additional information must not affect the image quality as this may cause the wrong diagnosis. The proposed algorithm contains one robust watermark for the ownership of the image and two fragile watermarks for checking the authenticity. The first two watermarks are embedded in the wavelet domain, while the third watermark is embedded in the spatial domain. In the proposed algorithm, the medical image is divided into two regions, called the Region of Interest and Region of Non Interest and all the three watermarks are embedded in the Region of Non-Interest. The new medical watermarking technique offers high peak signal to noise ratio and similarity structure index measure values. The technique was successfully tested on a variety of medical images and the experimental results show that the robust watermark survived many intentional and non intentional attacks, while the fragile watermark is sensitive to any slight tampering on the medical images.