Research On Technology Of Image Digital Watermarking Based-on Wavelet Transform

With the great development of computer technology and communication technology, it reaches our life. Digital information has the virtue of convenience, shortcut , and easily being copied, providing us with great convenience to acquire information and communicate with others. However, the rights and interests of the owner of the digital production and the legal user is violated. In order to protect the copyright, the technology of watermark becomes the focus of the field of the digital production. Although there has been a lot of investigation about it, the technology of watermark is far to maturity. Many problems have not been resolved.The digital watermarking technology based on spatial domain has characterics of computer briefness and bagger embedded capability, so it has been abroad studied in the first stage of watermarking technology. But gradually it has been replaced by watermarking technology based on frequency domain because of its disadvantage of robustness. The Wavelet Analyze can separate a spatial domain signal to some different frequency subbands by Mullti-Resolution Analyze(MRA), and Human Visual System(HVS) has the characterics of higher sensitivity to the lower frequency signal and lower sensitivity to the higher frequency signal. So the technology based on Wavelet Transform is often used to the ditigal watermarking field.The former men putting forward many algorithms have make great improvement in robustness or other aspects, but these algorithms have lack of the agility in the carrier capacity of system of watermark, the capacity of watermark, robustness, and invisibility. Aiming at this problem, in this paper we present a kind of image digital watermarking algorithms based on Wavelet Transform , we have had a experiment on the algorithms in the environment of Matlab and Photoshop. The result of the experiment shows this algorithms has great robustness to attack means of the sharp, filter, compressed JPEG2000, and with the different acquirement of watermarking system this algorithms, through fixed parameters, can harmonize relationship of the carrier capacity of system of watermark, the capacity of watermark, robustness, and invisibility.