Digital watermarking is a useful and powerful tool for multimedia security such as copyright protection, tamper proofing and assessment, broadcast monitoring, and fingerprinting. Many multimedia services are provided through wire/wireless communications, where transmission errors are present. Robustness of watermarking is a major concern during the transmission of watermarked multimedia messages. Multiple description coding (MDC) is a promising method for robust transmission of information over non-prioritized and unpredictable networks. As a source coding scheme, multiple description coding has been extensively studied and applied in audio, image, and video sources. It is also interesting to find that multiple description coding can be applied in multimedia watermarking. Recently several multiple description watermarking schemes have been developed which have exhibited some advantages. In this chapter, the concept, design algorithms, and some applications of multiple description coding are reviewed. Particularly, the application of MDC in watermarking, known as multiple description watermarking, is elaborated based on recent research results.
Digital multimedia information (text, audio, image and video) and applications have widely penetrated into our every-day lives in last decades. Advances in wireless communication, mobile computing and networking are providing us with business demands and opportunities for multimedia services. This has given rise to the urgent need for the creation and application of new methods for multimedia security. Digital watermarking is a useful and powerful tool for multimedia security applications such as copyright protection, tamper proofing and assessment, broadcast monitoring and fingerprinting (Kundur, 2001). However, the watermark could be damaged by incidental/intentional attacks during transmission. The robustness of the extracted watermark is a major challenge in the watermarking application. On the other hand, as one of the efficient error resilient encoding techniques, multiple description coding attempts to overcome transmission loss in applications where transmission channels are imperfect. Many audio, image and video applications using multiple description coding have been developed. In view of the strong error resilience of MDC, it is reasonable to applying multiple description coding in watermarking to improve the robustness of the extracted watermark. In this chapter, recent research results on the multiple description watermarking are surveyed.
This chapter is organized as follows. Section 2 introduces the concept, design algorithms, and some applications of multiple description coding. In Section 3, multiple description watermarking frameworks are categorized and discussed based on recent research results. Concluding remarks are given in Section 4.
Key Terms in this Chapter
Watermarking Attacks: Incidental or unintentional processes during transmission or delivery of the watermarked media are called attacks.
Multiple Description Coding: As one of error resilient encoding techniques, multiple description coding (MDC) attempts to overcome the retransmission problem in applications where transmission channels may not be perfect. A multiple description encoder generates two or more streams (known as descriptions) for one source. These streams are transmitted over separate channels respectively, and each can be individually decoded with a certain level of fidelity. Since these streams are also designed to complement each other, the incremental reconstruction quality is achievable with more received descriptions.
Watermarking: Watermarking is a well-known technique used to hide data or information imperceptibly within image, audio, or video so that valuable contents can be protected.
Multimedia Security: Multimedia communication plays an important role in multiple areas in today’s society including politics, economics, industries, militaries, entertainment, etc. It is of ultimost importance to secure multimedia data by providing confidentiality, integrity, and identity or ownership. Multimedia security addresses the problems of digital watermarking, data encryption, multimedia authentication, digital rights management, etc.
Multiple Description Watermarking Framework: It is a framework that applies multiple description algorithms to watermarking systems.
Iterative Coding of Multiple Description: Iterative coding of multiple description (ICMD) is a complicated MD algorithm, which is mainly designed to overcome channel impairments by using the correlation between the descriptions. Two correlated bit streams are decoded using two decoders which iteratively exchange soft information between each other.
Multiple Description Quantization: Multiple description quantization (MDQ) is one kind of multiple description algorithms. MDQ generally uses an index assignment function to create two or more representations for a symbol. Typical MD quantization algorithms include MD scalar quantization, MD lattice vector quantization, etc.