Abstract
This paper proposes a watermarking embedding and extracting methods in the frequency domain based on a selection of a high frequency range containing large amount of information. The selected high-frequency range contributes to the imperceptibility of the watermark while the robustness against compression is achieved because the selected frequency range contains large amount of information. The entropy-based algorithm is adopted to find the best tree of the wavelet-based contourlet packet transform (WCPT.) Such best tree represents the best basis of the WCPT whose corresponding frequency subband contains high information energy. In addition, for security aspect of the watermarking process, the bits of the watermark image is randomly permuted before embedding them to the selected subband. The key of the pseudo-random generator provides the security for the watermark. Each bit of the permuted watermark image are embedded to the original image by adjusting the WCPT coefficients of the selected subband, which also allows us to vary the level of watermarking. The proposed methods are tested with various benchmark images of various sizes and with various watermarking levels. The JPEG compression, Gaussian noise and filtering were applied as the attacks. Image Watermarking Based On Wavelet-based Contourlet Packet Transform With Best Tree has a higher imperceptibility than Image Watermarking Based On Wavelet Packet Transform With Best Tree measured in term of peak signal to noise ratio (PSNR) and higher readability measured in term of normalized correlation (NC).