Performance comparison of zerotrees based digital watermarking

In this paper, speech based digital watermarking using zerotrees of the rearranged discrete cosine transform (DCT), discrete wavelet transform (DWT) and wavelet packet transform (WPT) for digital images are studied and compared, in term of the quality of the resultant images and robustness against attacks. The PSNR is used to evaluate the quality obtained from the watermarked images, while the robustness is measured from the strength of attacks the embedded speech signal can survive. In this research work the contents contained in the speech is used to identify the specific information hidden in the embedded signal. The speech signal after being extracted from the watermarked images is played back to the listeners to determine whether its content is intelligible or not. The experimental results show that the watermarking scheme implementing the zerotrees of the WPT give the best performance, compared to the others.