Thanks to tremendous technological advances over the last decades, imaging systems are rapidly evolving, with each generation delivering greatly enhanced visual quality. In this context, three-dimensional (3D) imaging is often considered as a key feature in order to provide a more lifelike and immersive user experience (Dufaux et al., 2013).

However, most existing 3D technologies rely on stereoscopic or multiview representations. Unfortunately, these approaches have some fundamental limitations and only provide a limited set of depth-cues. As a consequence, user experience often remains below expectations. In addition, the inherent accommodation-vergence conflict, that is, the eyes are focusing on one point but converging toward another one, may induce headaches, nausea, or visual fatigue. These significant drawbacks explain the difficulty of 3D imaging technologies to gain momentum and broad market adoption in some application domains.

Holography was invented by Dennis Gabor in 1948 (Gabor, 1948). A hologram records the light field emanating from an object as an interference pattern. It subsequently allows reproducing this same light field and therefore reconstructing 3D views of this object which are theoretically indistinguishable from the original ones. Therefore, holography has the potential to be the ultimate 3D experience, with continuous head motion parallax, natural eyes accommodation and vergence, and all depth-cues including perspective, occlusions, lighting, shading, and defocus blur.

It is also worth mentioning two major milestones in the development of holography. The emergence of digital technologies made digital holography (DH) (Goodman and Lawrence, 1967; Schnars and Jüptner, 1994) possible. More specifically, rather than using a photographic recording, with DH the hologram is numerically recorded by a light-sensitive sensor such as a charged coupled device. Next, with the continuous computing power increases of modern computers, it became possible to simulate computationally the whole procedure. This is referred to as computer-generated holography (CGH) (Dallas, 1980; Tricoles, 1987).

Holography has been successfully applied in a number of applications, notably interferometric microscopy and metrology. However, major scientific and technological challenges remain before holography can fulfill its potential to become the ultimate 3D experience. For instance, signal processing issues for holographic 3DTV are discussed in Onural et al. (2007) and Onural and Ozaktas (2007). The development of holographic displays is also a key aspect for successful applications. Recent developments are presented in Bove (2012).

In this book, we more specifically consider the problem of representation and compression of holographic data. Indeed, digital holographic data represent a huge amount of information which has to be efficiently handled. In addition, a very high data rate is needed for a real-time system. These two drawbacks constitute major bottlenecks. Clearly, efficient compression of holographic visual information is a critical aspect. Given that the signal properties of holograms significantly differ from those of natural images and video sequences, merely applying existing compression techniques (e.g., JPEG or MPEG standards) remain suboptimal. This field of research is still relatively new and clearly calls for innovative compression solutions. This book aims at presenting a comprehensive overview of state-of-the-art compression techniques for digital holographic data, along with a critical analysis.

The book is structured as follows. In Chapter 2, fundamental principles of DH are reviewed. In particular, we present physical principles, CGH, and phase-shifting DH. Basic compression tools are briefly discussed in Chapter 3.Chapter 4 introduces and compares different representations of digital holographic data. The compression of digital holographic data is addressed in Chapter 5. More specifically, we review some quantization-based and wavelet-based approaches. Finally, some concluding remarks as well as open issues are discussed in Chapter 6.