Foreword by Henry Fuchs

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Henry Fuchs is the Federico Gil Distinguished Professor of Computer Science and Adjunct Professor of Biomedical Engineering at UNC Chapel Hill. He has been active in computer graphics since the early 1970s, with rendering algorithms (BSP Trees), hardware (Pixel-Planes and PixelFlow), virtual environments, tele-immersion systems and medical applications. He received a Ph.D. in 1975 from the University of Utah . He was a member of the faculty of the University of Texas at Dallas from 1975 to 1978. He joined the faculty at the University of North Carolina at Chapel Hill in 1978. He is a member of the National Academy of Engineering, a fellow of the American Academy of Arts and Sciences, the recipient of the 1992 ACM-SIGGRAPH Achievement Award, the 1992 Academic Award of the National Computer Graphics Association, and the 1997 Satava Award of the Medicine Meets Virtual Reality Conference. More information: http://www.cs.unc.edu/~fuchs

Foreword
I am pleased and honored to be invited to write the foreword to this excellent book. In fact, it is not merely excellent; it may well be the best ever comprehensive overview of computer display technology. If there is a better text on this topic, I have yet to see it.
Display technology is of increasing importance to all of us. We humans are acutely visual beings, and in todays' world displays are truly ubiquitous. Of course, twenty years ago we would already have said that they were "ubiquitous", but today they're even more so -- with mobile devices in every pocket, digital displays on every automobile dashboard, laptops and tablets with every student and adult, and large flat panel displays in every home and workplace. Stereo feature films are now commonplace and consumer televisions displays are increasingly 3D ready. And there is more to come--and soon. For those who wish to understand these technologies of today and tomorrow, this is the book to have and to study.
The authors wisely start the book by first whetting our appetites with a short history of display technology, starting around the Renaissance. Having captured our interest, they transition to an overview of the serious parts of this book. Chapter 2 starts with the fundamentals of light, light generation, color gamut, plasma lamps, phosphor, electroluminescence, and radiometry. Next, the fundamentals of the physics of light are discussed, including classic experiments about uncertainty and quantum effects -- surprising, but welcome topics in a book on computer display technology. Next, polarization and polarizing filters are described--ideas central to many computer displays.
Chapter 3 is a tutorial on the principles of optics, starting with wavefronts and diffraction, moving to reflective and refractive optics, including examples of concave and convex mirrors, and converging and diverging lenses, and also fresnel lenses. Also described are exciting new technologies such as varifocal "liquid lenses", which are applicable not only to miniature cameras in today's mobile devices but perhaps in the future, the authors point out, also to novel steerable autostereo displays (a topic treated in detail in Chapter 9).
Chapter 4 introduces visual perception. The authors include this topic in order to educate the reader to understand that display technologies always work through the human visual system; understanding that coupling is essential for the designer of any display system. Spatial and temporal and colorimetric response of the human visual system are covered in some detail. Stereo, depth perception, depth cues, and visual field effects are also explained, as are motion parallax and motion dynamics.
Holographic principles are covered in chapter 5. After presentation of basic principles, other topics are also described, such as holographic optical elements (HOE). These optical emulations of lenses, mirrors, and prisms are sometime used in display systems whose promoters label them "holographic." A variety of other holographic optical systems are also discussed.
Chapter 6 focuses on displays basics, with discussions of resolution, brightness, contrast, Gamma, color gamut, as well as wide-color gamut displays and luminescent and light valve displays. The chapter also includes a discussion of signal and image processing issues such as sampling, antialiasing, image compression, noise reduction; electronic issues such as passive and active matrix displays; and assembly issues such as touch sensing and tactile feedback.
Spatial light modulation is the topic of chapter 7, including LCDs, LCoS, DMDs and esoteric technologies such as PISTON-type micro-mirror displays and electronic paper. Projection displays are also covered, including projection optics and the various image-forming technologies: CRT, LCD, DLP, and others. Chapter 8 discusses camera-projector systems. Chapter 9 describes a wide variety of three-dimensional displays. All these chapters are solid, serious, sober. They cover material that is well-documented in the research literature and well understood from commercial products. The same characterization applies to the long (nearly 30-page) Appendix on image processing for displays, one that includes a discussion about GPUs and GPU-based algorithms for common raster graphics operations such as color space conversions and image distortion correction-- and much more.
The book's last two chapters are decidedly more colorful, wide-ranging, and speculative. The book's final chapter, on Discussion and Outlook, includes such "far out" possibilities as brain-computer interface, and retinal and neural implants. These ideas are casually tossed about in the general culture and in science fiction films, so if for no other reason, it is useful for the student of display technology to have some exposure to them from a more serious source.
The penultimate chapter, Chapter 10, on Near-Eye Displays, what many call head-mounted displays (HMD), is perhaps the most colorful and wide-ranging portion of the book, veering between sober discussion of current HMDs and their optical designs to "theoretical" discussion about holographic scanners and microprojectors implanted in the eyeball. Right in the introduction to the chapter, the authors forewarn the reader that after more than 40 years of research, a head-mounted display that's effective for widespread consumer applications still does not exist. The rest of the chapter is a study of the complex design issues and plethora of the conflicting constraints. A selection of optical designs used in commercial and research systems are described and illustrated. Sections on these are followed by several design studies developed by the authors. Designs to solve different problems are sketched out. The authors admirably include various caveats such as "The usefulness of most of these concepts has not been tested in practice thus far." An entire somewhat-speculative section is devoted to "Holographic image generation for NED." However, a following section, on NEDs that use of Holographic Optical Elements, brings the reader back to real, working, commercial display systems. The very next section (10.11), on contact lens displays, is among the most vivid in the book. The authors flatly state "some recent reports about actual 'contact lens displays' were greatly exaggerated." They then describe what has actually been demonstrated (very little) and speculate on paths toward realizing certain necessary developments. They consider several possible developments paths, including including miniature moving mirrors inside a thick contact lens, and even microprojectors implanted in the eyeball(!). None of these seem very feasible. They therefore conclude that "contact lens displays up to now are just mere speculation." However, our optimistic authors don't give up on finding some solutions to NEDs; they go on to describe various designs and technologies for adaptive displays (e.g., micro piezo motors) and eye tracking methods needed to control them. There is also a short section on video see-through displays (a topic that would benefit from more extensive coverage), and a section on the design of an optical see-through HMD that can mask out any parts of the real world that are occluded by pixels of virtual objects that are closer to the user. The authors end the chapter with a combination of sober conclusions (effective NEDs are "far off") and enthusiastic speculation about smart phones driving sophisticated NEDs with eye-tracking and eye-steering, of web pages "floating in space, hardly occluding the real environment. With a plastic front mirror and a totally integrated eye-tracker chip, this could all be affordable and simple." How can you resist such enthusiasm?
As with any comprehensive introductory text, the interested reader often yearns for more detail in many sections. The overwhelming reaction, however, is one of gratitude to the authors for compiling, distilling, and integrating such a large body of useful knowledge into a single volume and then enhancing it so substantially with ideas and designs of their own. They have produced a fascinating book, one that will be valued by serious students of the field for many years to come.

-Henry Fuchs Chapel Hill, North Carolina

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