Semi visible watermarking scheme based on DWT and PCA

In this paper, we have purposed a DWT-PCA based non-blind digital colour image watermarking scheme. We have developed two algorithms for embedding and extraction process. The original image is first DWT-decomposed, and then the colour watermark is implanted. Before embedding the watermark, the original image is segmented and principle component analysis is applied. Watermark embedding is applied in different frequency bands of the image and PSNR and NC plots are drawn for all the frequency bands. PSNR and NC are two parameters which define the correlation between the original image and watermarked image. A comparative study of plots of PSNR and NC shows that embedding in HL and LH bands is more robust and imperceptive than LL and HH band. Plots show the robustness of the scheme against various attacks. The main aim of this paper is to present a scheme for the purpose of copy right protection and authentification of the colour image data.