A New Scheme for Dual Watermarking using DWT-PCA Technique

In this paper, we propose a new scheme of dual watermarking by applying discrete wavelet transform and principal component analysis. For the embedding, we identify two best sub bands of wavelet transform by considering the intensity variance of each sub band. Two watermarks are embedded within the selected sub bands with respect to their principal components. Using dual watermark improves robustness and imperceptibility of algorithm and also takes advantage of using efficient bandwidth by embedding two watermarks into host image. Interleaving technique is used to improve imperceptibility of the algorithm. Experimental results show no visible difference between host and watermarked images. The proposed watermarking method is also robust to various attacks such as JPEG compression, cropping, histogram modification and gamma correction. This robustness is more noticeable when cropping or gamma correction applies to the watermark image.