Research On The Digital Watermarking Technology In Transform Domain

Digital Multimedia data have greatly enhanced the convenience of the storage of multimedia information, and variety of data can be delivered to the internet. However, the pirate problem has become more and more serious. Digital watermarking technology is the effective way to solve the problem which protect the data by hiding secret information in the digital multimedia (image, audio, video etc).Moreover, watermark algorithms based on transform domain can strongly resist the signal process and harmful attacks, and some algorithms combine the video compress standard. So the research of watermark algorithms based on transform domain has a good foreground.The research work focus on the digital watermark technology for color-image, and brings forward two watermark algorithms based on DCT and DWT. The theory, sort status quo and the feature of color-image have also been introduced. Appropriate human visual systems have been selected for embedding the information. An adaptive threshold watermark algorithm based on DCT which has perfect visual transparence and robust has been presented, and the security has been improved by Baker transform scrambling pretreatment. Also an algorithm based on DWT, image compress coding, human visual system (HVS), adaptive quantization has been presented, which embed color watermark image to color carrier image. And it has more robust owing to the characterization of majority and less computing. In addition, the conception of tamper detect has been introduced and the algorithm based on DCT has been ameliorated. It has good visual transparency and can detect the square tampered, also it can resist the normal image processing.