Digital Image Watermarking Algorithm

Digital watermark is a novel technique for protecting intellectual property rights. The copyright information—digital watermark is embedded into digital products to verify their ownerships. The embedded watermark information is usually invisible or imperceptible. However, a detector can be used to extract it or determine its existence. Recently, this technique has becomes a hot spot in research of multimedia information security.This paper addresses research of image digital watermark algorithm. The main tasks are summarized as follows:1. Make a study of chaos and disorder, and carry out these two techniques in the computer.2. Design and realize a digital watermark algorithm based on DCT transform by making full use of human visual system. This algorithm is carried out based on relation of intermediate frequency coefficient and its contiguous coefficient. And the detection of watermark doesn't need original image.3. Design and realize a digital watermark algorithm by making full use of wavelet packet principle. This algorithm embeds watermark information into the approximate coefficient of the tiptop resolving level.4. Put forward a digital watermark algorithm based on ridgelet transform. First, this algorithm uses Radon transform for original image. Second, this algorithm uses one dimension wavelet transform. Last, this algorithm embeds watermark information into the corresponding ridgelet coefficient.5. Put forward a digital watermark algorithm based on curvelet transform. First, this algorithm decomposes original image into four subbands using wavelet transform, and then selects LL₁ subband. Second, this algorithm uses ridgelet transform for LL₁ subband. Last, this algorithm embeds watermark information into the corresponding curvelet coefficient.Finally, we compare and analyze the experiment results of these four digital watermark algorithms. Experiment results indicate that watermark algorithm based on wavelet packet and curvelet transform in this thesis have certain value in theory.