The enormous popularity of the World Wide Web in the early 1990's demonstrated the commercial potential of offering multimedia resources through the digital networks. Since commercial interests seek to use the digital networks to offer digital media for profit, they have a strong interest in protecting their ownership rights. Digital Watermarking has been proposed as one way to accomplish this.
A digital Watermark is a digital signal or pattern inserted into a digital image. Since this signal or pattern is present in each unaltered copy of the original image, the digital Watermark may also serve as a digital signature for the copies.
In either case, the Watermarking of the document involves the transformation of the original into another form. This distinguishes Digital Watermarking from Digital Fingerprinting, where the original file remains intact, but another file is created that â€œbest describes" the original file's content. As a simple example, the Checksum field for a disk sector would be a fingerprint of the preceding block of data. Similarly, Hash Algorithms produce fingerprint files.