An Optimized Dual Image Watermarking Scheme based on Redundant DWT and Randomized SVD with Henon Mapping Encryption

Imperceptibility, embedding capacity and robustness are basic requirements of an image watermarking algorithm. There is always a trade-off among these requirements. To achieve a balance between these three properties in an image watermarking scheme, this paper presents a high capacity and encrypted dual image watermarking in YCbCr color space. This scheme is based on redundant discrete wavelet transform (RDWT), randomized singular value decomposition (RSVD), Manta ray foraging optimization (MRFO) and Henon mapping. Further, MRFO is utilized to get the optimized strength factor for embedding the watermark into the cover image to achieve high robustness and imperceptibility along with desired capacity. The luminance component of cover image is used to embed the watermark as it contains the vital information. Performance of the proposed scheme is evaluated for various medical and non-medical images in terms of imperceptibility and robustness. Different quality metrics are utilized to assess the performance of scheme. Various attacks are applied to check the robustness of the proposed method. Imperceptibility and robustness along with embedding capacity and computational complexity comparison with existing techniques are also presented. The comparison of MRFO with particle swarm optimization (PSO) is also carried out. Peak signal-to-noise ratio (PSNR) for all cover images is above 60 dB whereas Structural similarity index measure (SSIM) and Normalized correlation (NC) values are above 0.99 under no attacks. For non-medical images, the average percentage improvement in PSNR is 13.76% and in NC is 4.3% in comparison with other existing schemes. In case of medical images, average percentage improvement in PSNR is 41.35% and in NC is 0.62% when compared with related works. The proposed scheme is less computational complex in comparison with other existing schemes.