Research Of Color Image Digital Watermarking's Algorithms In Frequency Domain

Digital image watermark, as a branch of data hiding technology, imbeds symbol information into the protected image using the redundancy attribute of Human Visual System. As an effective approach of copyright protection of digital image, it has become a hotspot in the field of information security recently. Because of the attributes of invisibility, robustness and safety for the imbedded information, it is possible that the quality of the imbedded image is not destroyed after imbedding operation; meanwhile the ascription of copyright of the protected image is still available after some processing. Furthermore, with the development of the Internet and electronic business, digital image watermark, as an effective complementarity for the traditional cryptography technology, is getting more and more interest now.Frequency domain watermarking technology is the future trend. Previous research indicates that significant portions of the host image, e. g. the low-frequency components, have to be modified in order to embed the information in a reliable and robust way. This led to the development of watermarking schemes embedding in the frequency domain.My work in this paper is mainly about:I improve on two DCT domain image digital watermarking algorithms based on the principles of JPEG. The algorithm I is a private watermarking algorithm which need the original image in the process of extract the watermark .while the algorithm II don't need because it is a semi-private watermarking algorithm. In the two algorithms, the watermark is shuffled. Experimental results demonstrate the good robustness and transparency of the watermarking with the proposedscheme.Based on the wavelet theory, An algorithm of digital watermark in the wavelet domain is proposed. First the watermark is encoded utilizing Convolution Encoding. Then is embedded into the source image. When extracting the watermark, Viterbi Decoding of Convolution Decoding algorithm is applied. Because the channel coding principle in communication is used in this method, so greatly improve robustness and security. The experimental results show efficiency of the algorithm.