Non Blind Digital Watermarking Technique Using DWT and Cross Chaos

Watermarking techniques have been developed to protect digital images against illegal reproductions and illegal modifications. In this paper, a non-blind digital image watermarking algorithm based on Discrete wavelet transform, Cross chaotic map and Arnold transform, has been described. Initially, Discrete wavelet transformation is done and the medium frequency coefficients are extracted as the embedding field. Then, Arnold's transformation and Cross chaotic sequence are used to encrypt the watermark and the medium frequency coefficients of the watermark image are extracted to be embedded into the original image. It is a kind of non-blind scheme as the extraction needs the original image. Peak signal to noise ratio (PSNR) is used to evaluate the algorithm. The quality of the extracted watermark is evaluated using term Normalized cross-correlation (NC). From the results, it may be concluded that the modified algorithm is resistant enough against the common attacks. (C) 2012 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Department of Computer Science & Engineering, National Institute of Technology Rourkela