Multiple watermarking of medical images for content authentication and recovery

Medical image data require strict security, confidentiality and integrity when transmitted from one hospital to another hospital. This can be achieved by adopting the procedures which can guarantee the image quality as well as secrecy of patient data to unauthorized users. To achieve these requirements we have proposed a multiple watermarking method. The scheme embeds robust watermark in region of non interest (RONI) for achieving security and confidentiality. While integrity control is achieved by inserting fragile watermark in region of interest ROI. Since ROI in the medical image is important from diagnosis point of view so it must be preserved. In order to avoid the distortion caused in ROI due to watermark insertion process, original ROI data is first separated and embedded outside the ROI. This will help in recovery of original ROI at the receiving end in contrast to the techniques reported in the literature which do not guarantee the integrity of the ROI after watermarking process. The image visual quality as well as tamper localization has been evaluated. We have used weighted peak signal to noise ratio (WPSNR) for measuring image quality after watermarking.