**6. Rainbow – white light transmission hologram**

In this representational system the viewing zone is much smaller than for optical one- step holograms or HOEs. The viewing zone is of appreciable angular spread in one direction only in one direction, usually horizontal; in all other directions is is very narrow, only a few degrees.

Also there is a specific distance along the z-axis between the plate and the viewer at which the image seems best. As the viewer walks towards the holographic plane they tend to stop at this point, well away from the support. The basic characteristic of the image is that the subject appears in 3 D only in the horizontal plane, known as HOP horizontal parallax only. The image presents spatial information about the subject which accords with motion parallax, stereopsis, but not with the physiological cues of accommodation and fusion. The image is astigmatic, and, except in the case of the achromatic rainbow hologram, the colours change when the viewer moves along the y-axis.

Once the viewer walks out of the viewing zone the image appears to wipe off the plate. The viewer usually turns back and walks towards the other extremity of the viewing zone. Similarly, if the viewer moves above or below the narrow horizontal viewing aperture the image vanishes. The shape of this invisible aperture and viewing zone has been explained as a letterbox, a narrow wide slit aperture onto a volumetric scene.

subject projects forward towards the beholder. A constant dialogue between the reflected and diffracted colour of the two and three-dimensional surfaces are encouraged by the use of painting, both on the surface of the subject's skin and what appears to be on the

The holographic images are frontal and central, partly to give a classical, hieratic quality…a spatial image had to be merged with a flat image on the image plane, and a full frontal view

Benyon's work employs a synthesis between the monochromatic hologram and its underlay of a brightly coloured gauge painting. Full colour, either highly realistic or abstract through the use of multiple exposures with different colored lasers or by swelling the emulsion to

The latter technique,'pseudo colour' was employed to great effect in *Healing of Broken Hearts* (1985) by Melissa Crenshaw. Rather than hanging on the wall the work is mounted in a display case so it can be viewed from above. This evokes in the beholder the method of looking at precious items in a display case. The play of light over the intensely coloured surfaces is reminiscent of light playing on insect wings, or other Lepidoptera, a favorite subject of this type of hologram to demonstrate verisimilitude. The colours of Melissa Crenshaw's work are highly saturated, green, blue, violet, red and black and the composition remains static as the viewer moves. The formal arrangement of the colour along diagonals which intersect with a broken circle also encourages the beholder to circle

Crenshaw introduces us to a plastic, lineal and geometric holographic universe inspired on the first third of the twentieth century's constructivist and neo-plasticist avant gardes, a field restituted here by light. Colour acquires a structural and emotive function in an obvious

In this representational system the viewing zone is much smaller than for optical one- step holograms or HOEs. The viewing zone is of appreciable angular spread in one direction only in one direction, usually horizontal; in all other directions is is very narrow, only a few

Also there is a specific distance along the z-axis between the plate and the viewer at which the image seems best. As the viewer walks towards the holographic plane they tend to stop at this point, well away from the support. The basic characteristic of the image is that the subject appears in 3 D only in the horizontal plane, known as HOP horizontal parallax only. The image presents spatial information about the subject which accords with motion parallax, stereopsis, but not with the physiological cues of accommodation and fusion. The image is astigmatic, and, except in the case of the achromatic rainbow hologram, the colours

Once the viewer walks out of the viewing zone the image appears to wipe off the plate. The viewer usually turns back and walks towards the other extremity of the viewing zone. Similarly, if the viewer moves above or below the narrow horizontal viewing aperture the image vanishes. The shape of this invisible aperture and viewing zone has been explained as

different thicknesses between exposures is also a feature of reflection holograms.

is flatter than any other orientation of the head (Benyon, 1989).

the plate and interpret the composition from multiple view points.

**6. Rainbow – white light transmission hologram** 

change when the viewer moves along the y-axis.

a letterbox, a narrow wide slit aperture onto a volumetric scene.

holographic picture plane.

way (Carreton, 1996).

degrees.

It is not a straightforward matter for the beholder to locate themselves within this type of viewing zone. Sometimes a prescriptive approach has been taken. As Mark Diamond comments of early exhibitions at the Museum of Holography in New York.

…we did a lot of placing of little stickers on the ground… like those games where they show you how to tango, and where to put your feet; it was instructions on how to view the holograms, because people were unfamiliar with how to view the space (De Freitas, 2003).

These holograms are usually played back with a "white light" point source. Because of the dispersion of wavelengths over distance, when a white light source is used for replay, the image will be most focused at the hologram plane and become less focused in both + and – z.. This effect is more noticeable with large depth images. The decrease in resolution the closer the image protrudes into the + z space in front of the holographic plate is contrary to the experience of aerial perspective where the resolution of the image becomes less as it becomes more distant. Therefore although the cue of aerial perspective is not consistent with real-world experience, in practice it has little significance, because this cue is only significant over long distances and typically rainbow holograms are of a size that fits within personal or action space.

Rudi Berkhout's three colour rainbow holograms such as *Future Memories, Event Horizon* and *Toba* which include HOEs are types of landscapes in which elements undergo spatial transformations as the beholder moves from side to side. There is a use of a combination of types of H1, some of which portray abstract forms with a constant position such as fields of bubbles and others, which warp space in unpredictable ways.

In *Event Horizon* I was able to generate an image element totally by optical means. This was a breakthrough for me, for the first time I was able to draw with light. Starting with a point of laser light, I stretched multiplied and curved coil-like structures that I placed over a sphere (from a second master) in the final transfer. The third master used in this piece was of a forced –perspective field made of receding lines (Berkhout, 1989).

The spatial stability of randomly dispersed elements provides an alternate framework to the grid for navigating the space. Though on supports of modest size, like landscape paintings, the beholder's experience is that of traversing an immense and complex space.

For the most part these artificial light realities oppose the onlooker's perspective and visual habits. One reason for this is Berkhout's particular partiality for apparently impossible spatial arrangements of geometric bodies and forms… here Berkhout speaks of the creation of hyperperspective spaces (Lipp, 1985).

The complexity of these compositions has the effect of prolonged beholder engagement.

…for me part of the uniqueness of the holography is that the image is simultaneously there and not there, depending on the viewer's position…being able to see the work from the sides and from behind allows the viewer to examine and consider all angles of the image (Berkhout, 1989).

### **6.1 Colour**

The most striking feature of the rainbow hologram is that the same subject is seen in different colours according to the height in the viewing zone. The relationships of the different colours of separate subject elements are preserved, yet the colours themselves change. Colour behavior, because of its decoupling from stable relationships with surfaces of forms, probably cannot be processed by the brain in the usual way. As Zeki has shown the brain processes colour information in a very specific way:

The Visual Language of Holograms 347

Fig. 8. Dieter Jung, *Present Space*, 1986, Benton hologram, 42 X32cm.

The brain is principally interested in acquiring knowledge about the constant and invariant characteristics of a surface, namely reflectance. This it does by comparing the wavelength composition of the light reflected from it with the wavelength composition of the light reflected from its surrounds. By doing so, the brain is able to discard all the variation in the wavelength energy composition of the light reflected from a surface and assign a constant colour to it (Zeki, 2009).

If the colour of the form does not match the colour in memory then information is processed in another area of the brain. Zeki's results from functional MRI imagery of brain activity while viewing Fauvist paintings may serve as a model for understanding viewer response to rainbow holograms:

… I would like to draw another conclusion from the …survey of the Fauvist brain, which activates a distinct part of the monitoring system in the frontal lobes. I do not imply that this part is devoted to seeing Fauvist art, rather, it is an area that monitors the incoming information for any conflict with previous experiences (Zeki, 1999).

From these data it can be assumed that the way in which colour changes according to viewer position in rainbow holograms already activates the part of the brain which is concerned with abstract problem solving and resolving ambiguities.

In Dieter Jung's *Present Space* 1984 (Fig. 8.) the beholder sees an array of coloured horizontal bars of varying height and width- more widely spaced at the top and bottom (Fehr, 1991). The colour appears to exist in space without any material surface and is translucent. As the beholder moves from side to side the planes of colour overlap each other to generate new colour mixtures. There is no observable modulation of form of the colours in the z-axis. Jung makes sense of the wiping off of the image at the side edges of the viewing zone by locating two large black rectangles, one at the top and the other at the bottom of the composition, which are also empty.

The horizontality of the composition encourages a side-to-side motion in the viewer. The physical shifting of the beholder and the corresponding dynamic immaterial colour mixing of the composition is intended as an analogy to the "oscillation structure of the activity of our consciousness" (Fehr , 1991).

Doris Vila's *Chart: Space-Time-Sex-Money-Continium* monotype 1985 employs a one step rainbow hologram technique. The beholder of this very long 17 ½ x40 " image becomes immersed in layers of simultaneous narrative. The layers appear floating in the space between the viewer and the support, each of a different colour. The visual field holds in transparent layers overlapping stencils and found objects in multiple exposures; the translucency of these negative forms suspends them from concrete interpretation. The narrative metaphor is extended by the replacement of the usual white light replay source with a film loop of money falling into the image.

As Vila comments:

Most importantly the narrative line of the imagery was synthesized in the process of shooting, with many of the objects existing only for the moment of the shot; therefore the only record of their existence is the shadow they made at the moment of exposure. Some of the objects used were stencils of simply cut shapes that allude to natural phenomena, transparent forms of glass or plastic, fabrics and found objects…viewing the hologram is like adopting a memory, where each person's keys to the experience have a unique sequence (Vila, 1989).

The brain is principally interested in acquiring knowledge about the constant and invariant characteristics of a surface, namely reflectance. This it does by comparing the wavelength composition of the light reflected from it with the wavelength composition of the light reflected from its surrounds. By doing so, the brain is able to discard all the variation in the wavelength energy composition of the light reflected from a surface and assign a constant

If the colour of the form does not match the colour in memory then information is processed in another area of the brain. Zeki's results from functional MRI imagery of brain activity while viewing Fauvist paintings may serve as a model for understanding viewer response to

… I would like to draw another conclusion from the …survey of the Fauvist brain, which activates a distinct part of the monitoring system in the frontal lobes. I do not imply that this part is devoted to seeing Fauvist art, rather, it is an area that monitors the incoming

From these data it can be assumed that the way in which colour changes according to viewer position in rainbow holograms already activates the part of the brain which is

In Dieter Jung's *Present Space* 1984 (Fig. 8.) the beholder sees an array of coloured horizontal bars of varying height and width- more widely spaced at the top and bottom (Fehr, 1991). The colour appears to exist in space without any material surface and is translucent. As the beholder moves from side to side the planes of colour overlap each other to generate new colour mixtures. There is no observable modulation of form of the colours in the z-axis. Jung makes sense of the wiping off of the image at the side edges of the viewing zone by locating two large black rectangles, one at the top and the other at the

The horizontality of the composition encourages a side-to-side motion in the viewer. The physical shifting of the beholder and the corresponding dynamic immaterial colour mixing of the composition is intended as an analogy to the "oscillation structure of the activity of

Doris Vila's *Chart: Space-Time-Sex-Money-Continium* monotype 1985 employs a one step rainbow hologram technique. The beholder of this very long 17 ½ x40 " image becomes immersed in layers of simultaneous narrative. The layers appear floating in the space between the viewer and the support, each of a different colour. The visual field holds in transparent layers overlapping stencils and found objects in multiple exposures; the translucency of these negative forms suspends them from concrete interpretation. The narrative metaphor is extended by the replacement of the usual white light replay source

Most importantly the narrative line of the imagery was synthesized in the process of shooting, with many of the objects existing only for the moment of the shot; therefore the only record of their existence is the shadow they made at the moment of exposure. Some of the objects used were stencils of simply cut shapes that allude to natural phenomena, transparent forms of glass or plastic, fabrics and found objects…viewing the hologram is like adopting a memory, where each person's keys to the experience have a unique sequence

information for any conflict with previous experiences (Zeki, 1999).

concerned with abstract problem solving and resolving ambiguities.

bottom of the composition, which are also empty.

with a film loop of money falling into the image.

our consciousness" (Fehr , 1991).

As Vila comments:

(Vila, 1989).

colour to it (Zeki, 2009).

rainbow holograms:

Fig. 8. Dieter Jung, *Present Space*, 1986, Benton hologram, 42 X32cm.

The Visual Language of Holograms 349

Fig. 9. Martina Mrongovius, *Jumping Jellies*, 2007, rainbow stereogram, 30 X 40 and 60 x cm In both these installations I wanted the viewer to mimic ascending /descending in the image. The subject's (my) holding of the camera links the viewer's proprioception to the subject, establishing an emotional and imaginative connection of shared

In *Figure 8* the beholder is propelled at an increase speed in an office wheelie chair along a horizontal line parallel to the plate at the optimum viewing distance and in *Jelly*, the beholder jumps on a trampoline to fly past the small aperture located on the vertical y-axis. Here there is a deliberate reference to the inability to see the stereogram except from a

Falling, running, jumping and skipping are descriptions of movements but also come with strong emotive connotations. In the *Jumping Jellies* installations it is the physical mimesis between your own sense of blubber and the jellyfish movement that establishes the image. The intention of this work is both playful and to illustrate how proprioception can create a

Printed synthetic reflection holograms are composed from thousands of perspective views of a static or moving 3D scene. The viewing zone for these images is deep, the images being readable from both near and far with no particular point along the z-axis from which they seems best. The subject can appear in full colour and holograms are played back with a white light source. The side- to- side movement available to the viewer within the viewing

experience…(Mrongovius, 2009).

reading through experience (Mrongovius, 2009).

**8. Printed synthetic hologram** 

specific height.
