A Double Image Watermarking Based on Wavelet Domain and Krawtchouk Moments

In order to improve the robustness and invisibility of watermarkings embedded into the images, a novel algorithm is presented, which is based on discrete wavelet transformation (DWT). The original watermarking signal is embedded into the lowest frequency sub-band of the wavelet domain. Combined with the technique of encryption, the extracted Krawtchouk moment invariants of the image are used to establish another layer virtual watermarking and a mapping relationship between the two layer watermarkings. The mapping enables the self-restoration of the original watermarking with virtual watermarking when the image is attacked. The watermarking can be well extracted without the original host image. The invisibility and robustness of the proposed algorithm are demonstrated by the simulations, such as Gaussian noise, JPEG compression and some geometric attacks.