Research On Blind Watermarking Based On Image

The digital media has become a main way for information communication along with the wide use of network. At the same time, multimedia information security problems including copyrights piracy emerged as side effects of the popularity of digital representation and distribution over network. Information hiding, also called Steganography, digital watermarking technology and multimedia information encryption methods provide novel ways to solve these security problems for multimedia information.Conventional encryption systems usually encode the original files into the secret information, and then transmit them on the network. Because only the authorized users can decrypt the secret files, the original files are secure against the unauthorized attacks. But, for the multimedia files with a large amount of information, these schemes usually are so slow for encryption and decryption process. So it is important for us to propose some multimedia encryption and decryption systems combining to the character of the multimedia information themselves.The image information is usually stored in matrices. Two kinds of image encryption schemes base on chaotic sequence and matrix transformation are proposed. Chaotic sequences have several good properties including the ease of their generation, the sensitive dependence on their initial condition and the statistics property of noise. Because the proposed scheme uses block matrix transformation to encrypt images, it can scramble the grayscales and frequency domain. At the same time, it is very robust against distortion operations, for example, JPEG lossy compression, filtering, etc. It is another advantage for the proposed scheme with good property of localization for the possibly changed regions. The schemes satisfy the characters of convenient realization, less computation complexity and better security based on the theory analysis and vast test results.The multimedia encryption shemes usually randomize the original multimedia files to assure the security, but the digital watermarking technique is a different multimedia protection style, which embeds some digital labels or signatures into host multimedia data to guarantee that the copyright of host multimedia data isn't infringed.After analyzing the ordinary model, typical schemes and security of the digital watermark in detail, a type of self-adaptive watermarking systems is proposed. A new technique for the adaptive digital watermarking of still image is presented based on Human Vision System. According to the characteristics of the multi-resolution decomposition of the transformation, a scheme with use of a transform to embed vast signature information in different frequency bands of an image is purposed.