Chapter 42: Video Watermarking Overview and Challenges

Gwena l Do rr and Jean-Luc Dugelay
Multimedia Communications, Image Group
Eur com Institute
Sophia-Antipolis, France
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1. Introduction

If you hold a common banknote up to the light, a watermarked drawing appears. This watermark is invisible during normal use and carries some information about the object in which it is embedded. The watermarks of two different kind of banknotes are indeed different. This watermark is directly inserted into the paper during the papermaking process. This very old technique is known to prevent common methods of counterfeiting. In the past few years, the use and distribution of digital multimedia data has exploded. Because it appeared that traditional protection mechanisms were not anymore sufficient, content owners requested new means for copyright protection. The previous paper watermark philosophy has been transposed to digital data. Digital watermarking, the art of hiding information in a robust and invisible manner, was born. The recent interest regarding digital watermarking is demonstrated in Table 42.1, which reports the increasing number of scientific papers dealing with this subject. Today, entire scientific conferences are dedicated to digital watermarking e.g. "SPIE: Security and Watermarking of Multimedia Content". Moreover, even if it is a relatively new technology, some industries have already commercialised watermarking products e.g. the widespread Digimarc.

Table 42.1: Number of publications having the keyword watermarking as their main subject according to INSPEC database, July 2002.

Year	1995	1996	1997	1998	1999	2000	2001
Publications	2	21	54	127	213	334	376

Digital watermarking has first been extensively studied for still images. Today ,however, many new watermarking schemes are proposed for other types of digital multimedia data, so called as new objects: audio, video, text, 3D meshes…. This chapter is completely devoted to digital video watermarking. Since the main subject of this book is video databases, the reader is assumed not to be familiar with the concept of digital watermarking. Consequently, the fundamentals of the theory are presented in Section 2. Many applications of digital watermarking in the context of the video are presented in Section 3 in order to give an overview of the possible benefits that technology can bring. Section 4 lists the main challenges that have to be taken up when designing a new video watermarking system. Finally, the major trends in the domain, to the best knowledge of the authors, are reported in Section 5.