| With the rapid development of information technology and the mass multimedia datain broad-band computer networks, it is necessary to prevent illegal copying andrevising. The conventional cryptography methods can't help to solve such problem.Thus, the digital watermarking, a new technique is invented and arouses largeinternational interest.Digital watermarking embeds some information into the multimedia data in order toprotect the copyright. Generally it is demanded robustness and invisible.Reversible Digital Watermarking Technology not only recovers the primitive imagecompletely, but also recovers the marking image completely.Then, some important research results of digital watermarking are presented.(1) The definition and properties of wavelet are discussed. Its time-frequencyanalysismethod and multiscale property accord with human being vision system, whichmake it an ideal way for digital wartermarking. IWT makes the operation integral,ensures accurately restructure of the signal.(2) The scramble method is introduced the watermarking image's pretreatment. Thewatermarking image is scrambled by Arnold transform, which make the methodobtain the safety effect.(3) Improving the method of bit-planes cover-Media, reducing the destruction of theoriginal bit-planes furthest to drop the average change rate from 50% to 37.5%. Itincreases the quality without depressing the capacity of embedding information.(4) Aiming at the overflow problem of IWT, gives the conservative estimate methodin theory.(5) Giving a bit-distribute method base on HVS model, it is proved significant qualitywhile the capacity of embedding information is large.(6) Giving an application in distance experiment system, offering a good pledge ofthe security of the transmission. |
