Digital watermarking

Digital watermarking

ABSTRACT

Digital watermarking technology has been actively studied and developed by a number of institutions and companies since mid ‘90s. This area draws more and more attention as one of the key technology elements for content management, copyright protection and copy control of digital contents.

“Digital watermarking is a technique of embedding signals in digital data, that can be used to establish ownership or to ensure the integrity of the data.” The term digital watermark is in analogy to the watermarks that are used in the publishing industry. Most currencies, for example, have embedded watermarks that are difficult to reproduce but are visible in the correct viewing or lighting conditions. There are two kinds of digital watermarks: visible and invisible.

The watermark acts as an instrument to connect the a real world object to a digital entity such as a computer or the Internet. Detecting the watermark is akin to recognizing the object.

The process of digital watermarking involves the modification of the original multimedia data to embed a watermark containing key information such as authentication or copyright codes. The embedding method must leave the original data perceptually unchanged, yet should impose modifications which can be detected by using an appropriate extraction algorithm. Digital watermarks should be difficult to remove; resist a variety of signal processing attacks including compression, cropping, printing, transmission, rotation, scaling, etc. This paper is all about discussing these issues.

INTRODUCTION

Digital media has conquered the real world during the last years. Almost all forms of media can now be recorded in a digital format. The advent of digital photography, digital audio formats, and digital video formats have made it much easier to view and distribute the creative works of others.

However, digital technology has an aspect that functions both as a great advantage and a serious disadvantage at the same time. Digital media can reliably, easily and cheaply reproduced without fidelity losses. This is great because someone can easily copy and distribute his works/data, but at the same time, someone else can do the same without authorization, thus violating the creators’/owners’ Intellectual Property Rights (IPR).

Furthermore, the Internet growth has made the case even worse because of the great ease and speed in the distribution of the illegal content. A new technology called "Digital Watermarking" constitutes a valid solution to this problem, since it makes possible to identify the source, creator, owner, authorized user, as well as the distribution channels of digitized images, video or audio recordings thus securing and protecting various forms of digital media. Of the same companies that provide the watermarking technology, a copyright owner can find all illegal copies of their photos and music on the Internet and take appropriate legal action.

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