Research And Application Of Image Digital Watermarking Based On Chaos And DWT

Nowadays digital watermarking is an effective means to protect the copyright and verify the integrality of digital information, while the chaos sequence has many good characteristics, such as pseudo-random, unpredictability, high sensitivity to initial value, etc. So, by combining the chaos theory with digital watermarking, we can improve the security of hidden information.This paper chooses digital image as watermark carrier, and researches the classification of watermark and the application of chaos in digital watermarking. The main points are as following:Firstly, the chaos sequence is used to make fragile watermark. Because chaos sequence has high sensitivity to initial value, we used dual-value chaos sequence as fragile watermark and proposed a new fragile blind watermark algorithm. The algorithm improves the probability of tampering test further and has high sensitivity to image tampering.Secondly, we encrypt digital image using chaos sequence. A dual digital watermark algorithm is proposed. A fragile watermark was embedded in the digital image after a robust watermark had been embedded. The influence of the fragile watermark on the robust watermark was reduced by increasing the robustness of the robust watermark. In order to improve the safety and unperceivable feature of the robust watermark, we encrypted the watermark image using chaos sequence.Thirdly, we introduce the application of chaotic synchronization in digital watermarking. A method of making an asymmetric digital watermark based on chaotic synchronization theory is proposed. This algorithm improves the safety of the watermark information, and can prevent the attack which is based on the forecast method.At last, a relatively integral trade scheme based on asymmetric digital watermarking is proposed. The private watermark embedded in digital products may protects the merchant's interests of copyright; customers may identify the legitimacy of digital products online by using an asymmetric public watermark; the merchant can trace pirate by using the trade fingerprinting, and the fingerprinting may also prevent the merchant from bring a false charge against customers.