Nowadays, as the Internet grows rapidly, the copyright laws are not effective anymore, since a lot of copyrighted
products (picture, audio, video, document, etc.) are available as digital data. Any unauthorized parties able to
produce identical copies of digital data without degrading the original contents and to distribute the copies over
the network. This condition has led to a strong demand for reliable and secure distribution of digital data over
networks. Such a technique developed to overcome this problem is digital watermarking. Digital watermarking
is a process in digital domain, which embeds a watermark into a copyrighted digital data, to protect its value, so
that it cannot be used by unauthorized parties.
This paper is intended to give an overview on digital watermarking. First, three application fields of
watermarking are described and illustrated with some scenarios, namely watermarking for copyright protection,
watermarking for copy protection, and watermarking for image authentication. Then watermarking techniques
are discussed, starting from the basic watermarking procedure, followed by review of some watermarking
techniques. And later, some attacks and obstacles to watermarking are highlighted.
In conclusion, digital watermarking technology plays important role in content protection issues. Attacks and
obstacles are also had to be faced by this technology. The main obstacle is that there is no standard available for
watermarking techniques. Without any specific standard, it is difficult to determine how robust a watermarking
technique should be.