A Novel DWT Based Blind Watermarking for Image Authentication
S. Sujatha, M. Mohamed Sathik · 2012
Digital Watermarking is a technique which embeds a wa-termark signal into the host image in order to authenti-cate it. In our previous work [6], a watermark pattern was constructed from the information content of the image in the form of a Hankel matrix, but which was not robust against rotation operation. This paper proposes an in-novative watermarking scheme, in which low frequency subband of wavelet domain and the rescaled version of original image are utilized in the watermark generation process. A scrambled version of watermark is obtained with the help of Arnold Transform. The operation of em-bedding and extraction of watermark are done in high frequency domain of Discrete Wavelet Transform since small modifications in this domain are not perceived by human eyes. This watermarking scheme deals with the extraction of the watermark information in the absence of original image, hence the blind scheme was obtained. Peak Signal to Noise Ratio (PSNR) and Similarity Ratio (SR) are computed to measure image quality. In addi-tion, the competency of proposed method is verified under common image processing operations and a comparative study is made against the technique proposed in [6].