摘要：The rapid development of multimedia and internet allows for wide distribution of digital media data. It becomes much easier to edit, modify and duplicate digital information besides that, digital documents are also easy to copy and distribute, therefore it will be faced by many threats. It is a big security and privacy issue. Another problem with digital document and video is that undetectable modifications can be made with very simple and widely available equipment, which put the digital material for evidential purposes under question With the large flood of information and the development of the digital format, it become necessary to find appropriate protection because of the significance, accuracy and sensitivity of the information ,therefore multimedia technology and popularity of internet communications they have great interest in using digital watermarks for the purpose of copy protection and content authentication. Digital watermarking is a technique used to embed a known piece of digital data within another piece of digital data .A digital data may represent a digital signature or digital watermark that is embedded in the host media. The signature or watermark is hidden such that it's perceptually and statistically undetectable. Then this signature or watermark can be extracted from the host media and used to identify the owner of the media.
