An efficient medical image watermarking scheme based on FDCuT-DCT

In this paper, a blind medical image watermarking scheme based on Fast Discrete Curvelet Transform (FDCuT) and Discrete Cosine Transform (DCT) is proposed. FDCuT is applied on the medical image to get different frequency coefficients of its curvelet decomposition. On the high frequency curvelet coefficients of the medical image, block wise DCT is applied to get different frequency coefficients. Then mid band frequency coefficients of the medical image are modified by White Gaussian Noise (WGN) sequences according to watermark bit to get watermarked medical image. At extraction end, blind recovery of watermark data is performed by correlation of WGN sequences. The proposed scheme is tested for its effectiveness on various types of medical images such as X-ray, Ultrasound (US), Magnetic Resonant Imaging (MRI) and Computerized Tomography (CT). Result analysis shows that imperceptibility of watermarked medical image is better as PSNR is above 45 dB for all types of the medical images. In addition, the robustness of the scheme is better than an existing scheme for a similar set of medical images in terms of Normalized Correlation (NC). Experimental results show that scheme is robust to geometric attacks, signal processing attacks and JPEG compression attacks. An analysis is also carried out to verify the performance of the proposed scheme to support binary watermarks with different details in it: text and logos. Moreover, the proposed scheme resulted in zero false positive rate when tested on 100 non-watermarked images.