A Robust Double Watermarking Technique for Medical Images with Semi-fragility

摘要

This paper presents an innovative authentication technique for medical images based on double watermarking technology. The proposed multi transform based watermarkingtechnique utilizes Arnold Transform(AT), Discrete Wavelet Transform (DWT) and Discrete Cosine transform (DCT) leading to an enhanced robust double water marking technique with semi - fragility (RDWTSF) for medical images. The proposed methodology superimposes a spectral method (DCT) on a multi-resolution transform (DWT) while inserting the corresponding invisible watermarks onto the host image in two steps. Prior to these steps the host image is subjected to AT which reduces the spatial correlation among the pixels of the host image by disordering their location which retain many coefficients DCT and DWT making them suitable for computation and realizes high-quality, robustness and semi-fragility successively in the watermarked image. The pair of watermarks include the ownership (ECG/Hospital LOGO) and verification details (patientid) respectively. The intermediate steps of RDWTSF involves the forward and inverse operation of the corresponding transformations. Finally, the watermarked image is realized through inverse of AT which is transmitted across noisy channel. On the receiving end these transformations are applied in reverse order to retrieve the watermark from the watermarked image. The experimental results show that ownership is survived despite the attacks which is considered to be robust authenticity and causing a distortion in patent id, corresponding to semi-fragility. The sanctity of the RDWTSF is presented by conducting experiments on benchmark images and extracting the PSNR, NCC, and SSIM measures.