Non-blind Arnold scrambled hybrid image watermarking in YCbCr color space

Due to fast technological development, human beings generally depend upon computer and other digital equipments in different areas of concern/applications. Therefore, various issues related to authentication and information security are raised with multimedia content in defence as well as in civil arena. In present work, a non-blind Arnold scrambling incorporated hybrid image watermarking technique has been proposed to improve the security and robustness. Here, color image as a watermark has been used instead of binary or gray image. To enhance the correlation between original host/cover and watermarked image, YCbCr color model has been chosen to separate channels of RGB image. Y channel has been used for embedding the singular values of watermark into the corresponding value of host/cover image using variable scaling factor (alpha). For more security aspect, number of iterations in Arnold transform have been included as a key for scrambling the watermark image prior to its embedding. Present work requires the original image for extraction of watermark hence the proposed work comes into the non-blind category. To calculate the imperceptibility, fidelity parameters such as; peak signal- to- noise ratio (PSNR) and structural similarity (SSIM) have been chosen whereas normalized correlation coefficient (NCC) have been used to calculate the similarity between original and extracted watermark. For robustness check, the proposed technique has also been tested against various attacks. The simulated results have also been compared with some of the existing color image watermarking techniques. The experimental outcomes prove the usefulness of the proposed image watermarking technique.