Digital watermarking using zerotree of DCT

Watermarking technique has been proposed as a method to embed an invisible signal into multimedia data so as to attest the owner identification and di scourage the unauthorized copying. In this paper, an efficiently DCT based watermarking technique is proposed. In the proposed method, we take the adv antage of zerotree in the rearranged DCT coefficients to embed watermark in to image and extract watermark from watermarked image more efficiently. The proposed method can directly extract the embedded watermark from the water marked image without using original image so as to implement it to the real time system is feasible. And a scheme of spreading watermarking informatio n is also used to provide the robustness of digital watermark. The experime ntal results show that the imperceptibility and robustness of the digital w atermark can be guaranteed.