**1. Introduction**

Any medium which represents three-dimensional space via a two-dimensional plane employs a representational system. Perspective, a system in which lines, which recede from the foreground to the horizon, create the illusion of depth by converging to the vanishing point has become the dominant means of representing space in western civilisation. Just like other representational systems, display holograms represent space in an abstract way through a series of conventions, which are defined by recording procedures and replay methods. The holographic representational system is so radically different from perspective, enabling the subject to appear in front of, straddling, or behind the hologram plane, that at times it seems invisible to viewers who believe they see the subject by a kind of magic. Even astute theorists, Umberto Eco (Eco,1987) who saw holograms as *hyperreal*, and Jean Baudrillard (Baudrillard,1997) who thought of them as *simulacra*, were implying that the hologram did not have a representational system, that it was a replica of reality. Though holograms can have a high level of spatial verisimilitude, this is variable, as is the resolution, spectral range, blur and the shape and location of the viewing zone.

A primary aim of this chapter is to introduce the properties of the representational systems of several hologram types, including HOE holographic optical elements, laser transmission, white light reflection, 'rainbow' white light transmission, white-light transmission holographic stereograms and printed synthetic holograms. Secondly the chapter will trace how the expressive potential of pictorial qualities such as light and darkness, transparency, reflections, colour and impossible forms operate within these representational systems. Case studies by artists such as, Margaret Benyon, Rudie Berkhout, Brigitte Burgmer, Salvador Dali, Paula Dawson, Jacques Desbiens, Mary Harman, Dieter Jung, Eduardo Kac, Martina Mrongovius, Seth Riskin, Andy Pepper, Martin Richardson, James Turrell, Doris Vila and Sally Weber will be examined.

Occasional comparison will be made between the effect of using the same pictorial qualities – light, darkness, transparency, reflections, colour and impossible forms in holograms and in other traditional media. Thirdly, the chapter looks at some factors, which are likely to impact on viewer reception and interpretation of the visual language of holograms: the bodily experience of interaction with the holographic image, the physiological and psychological aspects of depth perception and other influences such as historic genres and the associations of related media.

The Visual Language of Holograms 331

Beaudrillard's and Eco's discourses, which set the tone for the appreciation of display holography, do not describe the specifics of holographic representational space. Rather they

…as you shift your gaze you can see those parts of the object that you were prevented from glimpsing by the laws of perspective... Holography could only prosper in America, a country obsessed with realism, where, if a reconstitution is to be credible, it must be absolutely iconic, a perfect likeness, a "real' copy of the reality being represented (Eco, 1987). The hologram simply does not have the intelligence of trompe l'oeil, which is one of seduction, of always proceeding, according to the rules of appearances, through allusion to

Underpinning the arguments of simulacra and hyperreal is the assumption that a hologram replicates or simulates reality, leaving no room for cultural interventions such as expression and abstraction, or a representational system, and by extension no potential for conceptual

By contrast, from the above example, *The Broken Window*, it is clear that the hologram is not necessarily a replication or simulation of a physically real thing, that its referents can be highly conceptual and in fact engaged with the very nature of its representational capabilities. The potential offered by the synthetic hologram's representational system clearly extends the scope of the functionality of the hologram well beyond *simulacra* and *hyperreal*. The representational systems of laser transmission holograms, holographic optical elements, one and two step reflection holograms, rainbow holograms and white-light transmission stereograms each operate in a different way and therefore make available other types of compositions. But before examining the specifics of holographic representational systems it is useful to first establish the basics of representational systems in general. These are firstly their formal abstract properties, secondly the way in which these interface with

Fundamentally, representational systems are abstract codified means by which spatial and temporal information can be represented and interpreted. They underpin the majority of the images we see. Representational systems can be employed in hand-made works such as drawings and paintings, or through optical/digital photography, film, computer generated environments, video and diffractive holograms. Depending on the representational system used, the same subject matter can have quite a different appearance. For example, visually, the image of a house using the representational system of perspective would differ from the same house rendered in oblique projection, because in perspective the rules of abstraction dictate that the lines running away from the viewer will converge to a vanishing point and in oblique projection these lines remain parallel. Both achieve the objective of abstracting the three-dimensional space in such a way that the viewer can deduce that the two-dimensional

In each case the representational system shapes the way in which information about the subject will be formed into an image. In some cases the properties of one representational system can be used across many media. Perspective for example can be applied to drawings, painting, computer graphic environments and holograms. Traits of some representational

We have seen that there is a range of examples of holograms, which engage in a didactic or overt way with other representational systems, such as *The Broken Window*. Early optical holograms such as Bridget Baumer's work *Leonardo's Baby* a "Denisyuk" reflection

the beholder and finally the meanings which are ascribed to them.

systems can also be quoted or appropriated in others.

describe the effect as a *simulacra* or a part of a kitsch trend towards the *hyperreal*:

and ellipsis of presence (Baudrillard, 1997).

content.

image signifies a house.
