A secured robust watermarking scheme based on majority voting concept for rightful ownership assertion

A novel secured robust blind watermarking scheme has been proposed in this paper. It exploits the human visual system (HVS) insensitivity to detect color changes as compared to brightness changes for embedding of watermark. The color space is converted from RGB to YCbCr and one of its components is chosen arbitrarily for hiding copyright information. The scheme is made very secured by Arnold chaotic maps and usage of multiple secret keys. Three diagonal pairs of discrete cosine transform coefficients are chosen in each sampled block of the color channel and a threshold criteria based embedding is done in each pair corresponding to a single bit of the encoded copyright information. To handle various image processing attacks and enhance robustness of the scheme, extraction of the watermark bits is done based on majority voting concept using two separate counters for representing watermark bits. The efficacy of the proposed scheme has been tested against variety of image processing and geometrical attacks and evaluated using peak signal to noise ratio (PSNR), structural similarity index matrix (SSIM) and normalized cross correlation (NCC) metrics. Comparative results based on different aspects of robust watermarking scheme is also presented to build the appropriateness of the proposed scheme over existing state of art approaches.