  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.
