In this paper, we propose two methods of digital watermark for image signals based on the wavelet transform. We classify wavelet coefficients as insignificant or significant by using zerotree which is defined in the embedded zerotree wavelet (EZW) algorithm . In the first method, information data are embedded as watermark in the location of insignificant coefficients. In the second method, information data can be embedded by thresholding and modifying significant coefficients at the coarser scales in perceptually important spectral components of image signals. Information data are detected by using the position of zerotree's root and the threshold value after the wavelet decomposition of an image in which data hide. It is shown from the numerical experiments that the proposed methods can extract the watermark from images that have degraded through several common signal and geometric processing procedures.

With the advent of digital video and digital broadcasting, copyright protection of video data has been one of the most important issues. We present in this paper a novel method of digital watermark for video data based on the discrete wavelet transform. In this method, we embed the watermark in the lowest frequency components of each frame in the uncoded video by using a controlled quantization process. The watermark can be extracted directly from the decoded video without access to the original video. Experimental results show that the proposed method gives the watermarked image of better quality and is robust against MPEG coding and re-encoding. Furthermore, we discuss multiple watermarking with regard to the generational copy control for video contents.

We have developed a low bit-rate video coding using a video digital signal processor (DSP) called VDSP1χ, which performs real-time encoding and decoding for discrete cosine transform-(DCT-) based algorithms, such as ITU-T H. 261, H. 263 and wavelet-based subband encoding algorithms. This LSI features a processing unit which implements wavelet filters at high speeds, a compact DCT circuit, and a fast, flexible DRAM interface for low-cost systems. This system is capable of processing quarter common intermediate format (QCIF)(176144 pixels) size pictures at a rate greater than 15 frames/s.