Before Our Eyes (part 2)

Psychophysics of Colour

To reproduce a single colour frame of moving image, a DLP projector overlays three discrete images in quick succession, their output synchronised with the motion of a filter wheel divided equally into segments of red, green and blue, the three primaries that correspond with the colour sensitivities of our retinal cones. From a technical perspective the full colour image that we perceive never exists, but is only created in the audience’s perception by additive colour synthesis.  From the perspective of the machine there is only of a sequence of distinct red, green and blue images, whose intensity is micro-managed at the level of the individual pixel. Colour, as experienced in both DLP projection and unmediated human perception then, is never ‘true’ (as BenQ claim), but always a technical construction.

Through processes such as this, the production and reproduction of the digital image is founded on an externalisation of our perceptual faculties. Digital image technologies are designed so explicitly to be seen, that their technical specifications not only reflect but directly imitate the anatomical construction and perceptual effects of human vision. The pixelation of a digital micromirror device (DMD) reproduces on an optoelectronic grid the mosaic of cones lining the retina, while the colour wheel enforces a trichromatic filtering that targets their colour sensitivities. We can therefore conceptualise the optical mechanisms of a DLP projector as an attempt to build a projecting eye, a luminous electronic retina radiating colour onto the surfaces of its environment.

The optical principles on which this mechanism is based originate in the trichromatic theory of vision, hypothesised by Thomas Young in 1802 and subsequently proven through the psychophysical experiments of Hermann von Helmholtz and James Clerk Maxwell. The colour triangle, initially posited by Young  (below, left) to describe colour spatially as created between the three poles of red, green and – as he supposed – violet has now become a standard means of measuring the colour gamut of various display technologies, in which different technical standards can be described as differing sizes of triangle within the complete perceptual colour space circumscribed the CIE system (below, right).    

This chromatic space postulated by Young was subsequently mapped empirically by Maxwell. To conduct his experiments, Maxwell constructed a handheld wheel (below, left) onto which could be clipped overlapping discs of different colours. The wheel was then spun fast enough that the colours mixed together in the perception of their observer in much the same way that the discrete frames of a moving image appear as continuous motion. Using this simple instrument, Maxwell was able to quantify the perceptual effects of different ratios and combinations of the three primaries. In so doing, Maxwell ascribed numerical values to the proportions of vermillion, emerald and ultramarine used to achieve different tones, shades and hues; producing a series of discrete values within a field of subjective experience that had previously been understood as a continual spectrum. To quantify colour in this manner can be understood as a kind of proto-digitisation, and Maxwell’s method prefigures the numericalisation of colour gamuts in media technical standards from the 216 ‘websafe’ colours to the considerably wider gamut of 16 million colours that can be coded in a six digit RGB hex code.

Maxwell’s conclusion from these perceptual experiments: “that the judgment thus formed is determined not by the real identity of the colours, but by a cause residing in the eye of the observer” (link) established human vision as a manipulable system of perceptual limitations. This psychophysical conception of sight as fallible and slow relative to mechanical motion persists throughout our contemporary media environment, and is the foundation on which all moving image technologies rely. And – in the colour filter of DLP projectors (below, right) – Maxwell’s colour wheel persists today as a techno-chromatic mechanism of externalised sight. A spinning disc originally used to measure the chromatic operation of the human vision has now become a central component in the reproduction of projected colour. The dissolving of biological sight into its trichromatic primaries was diagnosed by the exact same mechanism that now resolves those colours before us.

In 1855, when black and white photography was still in its experimental infancy, Maxwell proposed a system for producing a colour photograph. By photographing the same scene through three separate red, green and blue filters and then, using magic lanterns, projecting each result through its respective filter on top of one another, he hypothesised that a full colour image could be produced. This process was successfully demonstrated six years later creating a now much reproduced image of a tartan ribbon. In DLP projection each frame of the moving image replicates exactly Maxwell’s process of additive colour synthesis, combining three discrete monochromatic images in the audience’s perception. Maxwell’s trichromatic system of projection is now automated by contemporary cinema to occur, in some systems, as often as ten times for every frame, or 250 times a second.

Such accelerations of photographic temporality began, as Paul Virilio writes, from the moment of its invention: “from Nièpce’s thirty minutes in 1829 to roughly twenty seconds with Nadar in 1860” (p. 21), and rapidly continued past the frame rate of film projection to now operate habitually at rates far beneath human temporal perception. If celluloid cinema enabled the capture of movement by the intervention of a rotating shutter, fragmenting time into a sequence of freeze frames, then in DLP it is this now historic whole of the individual frame itself whose unity is dissolved both spatially into pixels and chromatically (and, as we will see in next post) temporally into three subsequent perceptual primaries. 

Before Our Eyes (part 1)

A 2018 BenQ home cinema advert begins with a white middle-aged man (with whom the target market is presumably meant to identify) settling down in an armchair next to his projector to watch three cinematic clips, each with carefully managed near-monochrome colour spaces. The first, captioned BLUE MONDAY, stands for introspection, solitude, and melancholy; the second, RED VALENTINE, for passion, drama, love and loss, the third, GREEN MIRACLE, for the awe of the natural world, as embodied by the aurora borealis, whose cosmic light phenomena BenQ are at pains to analogise with their new digital light processing (DLP) projector. The ad then cuts – in a manner popularised by late twentieth century shampoo commercials – to a computer animation of the internal technics of the projector. This sequence begins with a close-up of the viewer’s eye that quickly fades to a similar perspective on the projector lens. Beams of white light flash across the screen as the camera appears to track back into the machine, falling on a spinning colour disc divided into 6 segments, two each of red, green and blue (RGB). Moving alongside this disc, the white light is shown as consisting of these three primaries. We cut to a second animation, this time of a digital micromirror chip seen from above, a saturated spectrum of digital light reflects of its surface with an accompanying swoosh, as the earnest voiceover informs us that “only true colours convey the deepest feelings”. At this point the ad cuts back from animated to cinematographic images, now in saturated technicolour, flashing between clichés of strolling through the Casbah, a sunset embrace, playing in autumn leaves, a newborn yawn, a kiss on a window pane. Obscured behind its hackneyed equivalences of emotion and colour, and yet hinted at by the knowing analogy between human eye and projector lens, is a far deeper historical and technical connection between physiology and projection. As Henning Schmidgen has shown this connection in fact dates back beyond the invention of cinema to 1872 when German physiologist Johann Czermak pioneered the use of projection in what he called his Spectatorium: “a fragmentary cinematographic apparatus consisting of projector, screen, and rows of seats”. In this mediatised version of an anatomy theatre “cells, tissues and organs functioned in the place of recordings on celluloid” (p44). Schmidgen goes on to describe an arrangement of an eviscerated frog’s heart, two mirrors, lenses and a light source that projected an enlarged image of the contracting heart – removed from the frog’s body but still connected to its nerves – onto a screen above the audience. 

In the decades that both preceded and followed this anecdotal convergence of projection and physiology, experimental discoveries about human physiology were made by, among others, James Clerk Maxwell and Hermann von Helmholtz which comprehensively undermined the conception of human sight as objective and transparent, insisting – and indeed proving – its complexity, subjectivity, and its flaws. In these posts I will discuss the technical correspondence between the operation of DLP and human visual perception, with a particular emphasis on how contemporary projection has instrumentalised the knowledge of nineteenth century psychophysics, showing how the technical specifications of DLP projection are derived from a history of the empiricial measurement and quantification of subjective phenomena. This relationship is emblematic of what Jonathan Crary has described as “the reconfiguration of optical experience into synthetic and machinic operations that occur external to the observing subject” (p.226). The literal externalisation of the still beating heart in Czermak’s projections precedes a less violent externalisation of sight in the technics of contemporary projection. However, whereas in Czermak’s Spectatorium the frog heart projections served to demonstrate anatomical function through direct visual reproduction, in the case of DLP, knowledge of human physiology is used to ensure that its operation remains imperceptible to its audience. So, while for Czermak, projection was a transparent tool of instruction, the spectacle of DLP projection relies on the opacity of its technics to maintain the spectacle of its moving image. The psychophysical discoveries of Maxwell and Helmoltz are inscribed in DLP as a series of chromatic principles and temporal intervals within which certain operations must be occur to retain the illusory nature of its image. Whereas in the nineteenth century projection served to reveal physiological operations, projection now uses nineteenth century knowledge to conceal its operation.




On Detritus

Constant Linear Velocity installed at the Onassis Cultural Centre for Detritus Festival, January 2018.


This text is the sleevenotes written for the publication of the Constant Linear Velocity CD on Consumer Waste, which discusses the experience of rebuilding the work in January 2018 for the Detritus Festival:

The six floor cube of the Onassis Cultural Centre stands on Sygrou Avenue, an eight-lane artery running between central Athens and the coast. Opposite, flanking the hotel where I am staying stand two strip clubs: Babylon GIRLS Live Show GIRLS Night Club & the Everything you want right now!!! Dream Girls Bar, whose sign is bullet-pointed with all five senses, in case you doubt their definition of everything. Amongst the 4 star hotels, car showrooms and strip joints, the OCC, wrapped in pinstripes of white marble, is incongruously opulent.

I am here to reconstruct a work made from numerous empty desktop computer cases using end-of-life machines sourced in the city. Even on the brief walk out for dinner last night it was clear that this work has considerably more poignancy in a city and country which has borne the brunt of the last decade’s financial meltdown in Europe. I have arranged with the festival producers for the hire of 120 or more desktop computers stripped down to just their metal chassis in which I will install the customised optical drives that form the kinetic and auditory content of the work. When I arrive in the morning they are being wheeled in and unloaded, but my instructions to strip down the machines in advance have been lost in translation, most of the plastic and electronics remains.

For the next eight hours I perform the labour of low waged e-gleaners on the polished marble of the 4th floor foyer. Systematically stripping out disc drives, power supplies, fans and USB ports, occasionally watched by an increasingly concerned production team as the volume of discarded components swells into heaps. In the dynamic established by the global electronics industry this work is supposed to be invisible, it happens in the margins and the fringes, not the foyers of a ‘Centre’. For some of the OCC staff, I sense there is something shameful in this relocation of salvage labour to the gleaming interior of their privately financed art space. But this performance of manual labour, whose audience is restricted to workers of the Cultural Centre, feels more vital than the aesthetic work I am here to build for a festival attending public. Over the course of the day there is a satisfying inversion in play as cleaners, caretakers, security and reception staff – all doubtless earning less than me today – drift pass or linger to watch me hurriedly tearing down PC after PC.

I try to sort and stack the components as they come out, but the quantity regularly exceeds the spaces I have allocated. A janitor with a large roll of corrugated card is instructed to cover the floor I am working on to protect against scratches (casing screws skittering across marble make a lovely sound). Halfway through the day my proposal to keep all of this detritus, to  build it into the work, raises concerned brows from the production team and by the end of the day I am talked out of it. A team of men arrive, all hands on hips, rolled eyes and muted sighs. After the customary mutterings and gesticulations they bag it all into large rubble sacks and wheel it away, trolley-load after trolley-load. But as it is tided out of sight, the emptiness of the computer chassis feel stripped, not only of the functional parts and coagulates of dust which clung to them this morning, but also of the hierarchies of labour revealed by the day’s activity.

The next morning, to the palpable relief of the production team, I am safely back in art worker role, able to contemplate  the architectonic relation of the sculpture to the aggregated polykatoikia lining the horizon. The fringes of Athens, we are told a couple of days later, are dense with unfinished buildings, holiday homes begun over a decade ago whose completion was curtailed by the crash. Windowless, unfurnished concrete shells, projections of a future that has been denied.