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Before Our Eyes (part 3)

Lost Time and the Artificial Present

For such a system to succeed, the speed of our nervous impulses must be exceeded by the rate of the stimulus. In DLP systems two distinct frequencies combine, both well above the temporal resolution of human sight. The colour wheel revolves at a frequency of approximately 120 revolutions per second, while the micromirrors on the DMD chip dither at a frequency near 10,000Hz. When media technical operations so routinely outstrip human temporal resolution, the instantaneity so hard sought by the photographic industry during the twentieth century loses its meaning. The appearance of an image on the screen of a digital camera is now fast enough to be commonly described as instantaneous, at least with reference to our perception, yet it conducts many operations of correction, optimisation, reduction, and compression on each image before it is displayed on the screen. Even ‘an instant’ has become an interval capable of being instrumentalised by image processing algorithms.

The micro-temporality of these technical operations is also predicated on a physiological understanding of human perceptual response established in the nineteenth century by Helmholtz’s measurements of stimulus and response. Prior to these experiments, nerves were presumed to transmit stimuli instantaneously around the body. Contrary to this presumption, Helmholtz “aimed at investigating this alleged instantaneity more closely and, if possible, to define it more precisely” (p. 61-2). To conduct this research Helmholtz first constructed an apparatus assembled from a sample of frog muscle, a rotating cylinder and a steel stylus (see image below). When the muscle was stimulated with an electrical impulse, its contraction caused the stylus to inscribe a curve in a soot-coated transparency that was wrapped around the clockwork-driven brass cylinder. From these curves it was possible to observe, and indeed measure, for the first time, a gap between sensation and resulting movement – cause and muscular effect – a gap which Helmholtz figured as temps perdu. Helmholtz’s subsequent experiments with human subjects measured a surprisingly consistent delay between stimulus and response of 0.12 and 0.20 seconds. Helmholtz’s repetition of these experiments in different areas of the body led him to conclude that “in humans the ‘message of an impression’ propagates itself to the brain with a speed of circa 60 meters per second” (p.144). The limit speed of lived experience was revealed and defined by a machine that hybridised the mechanical with the organic, stimulating the latter with electricity. Such precise measurements of physiological time were only made possible by the twin technics of clockwork and the electrical telegraph, time had to have been mechanised and the body conceived as a network of electrical impulses before the duration of human nervous impulses could be measured. Media again precedes the mechanistic understanding of physiology.    

In the context of digital technologies this temps perdu, the lost time of bodily reaction, has too become externalised in an array of buffers, caches, and shift registers that all serve – be it in an operation of image capture, video playback or networked communication – to delay the materialisation of the instant in temporary stasis while it is archived or resynchronised by the time signature of the machine. And, due to the wide discrepancy between embodied temporalities and media-technical frequencies these momentary delays are opportunities for further computation, or as Wolfgang Ernst puts it: “suspended in memory, time becomes mathematically available” (p. 28). To a chip whose clocking frequency is 10,000Hz, even the fastest possible human response time of 0.1 seconds represents a significant opportunity. The psychophysical quantification of a lag between stimulus and response enables the acquisition of the ephemeral by the logic of the machine. It is within this temps perdu that the processes of encoding, optimisation and compression are all achieved. As Florian Sprenger writes: “the fact that transmissions are constantly interrupted means that they are never completed in putative real-time … and that we have no direct access to the world we are connected to” (p. 20-1). Experience is extracted into memory before it registers in the mind.

What does it mean for an image to be instantaneous when it is routinely manipulated in advance of being seen?  What is our experience of time when these operations are continually occurring in an imperceptible buffer before the screen? This is neither the time of the phenomenological present, nor the time of the live electronic broadcast, but time dissected, quantized and reconstructed in pre-instantaneous moments before our very eyes. For Ernst this means that “computing dislocates the metaphysics of the pure present to a micro-deferred now” (2018: 35). As Ernst shows in Chronopoetics, synchronicity was vital to the time-image of electronic television, but in the individualised playback of digital media synchronicity dissolves into myriad individualised timelines whose buffers and connectivity resynthesise the impression of synchronicity on demand. The live has been replaced with the live-like, a parallel temporality that slips in and out of sync with the now, in and out of sync with its soundtrack, in and out of sync with others.

In his analysis of The Helmholtz Curves, Schmidgen analogises Helmholtz’s method to photography, noting that these experiments both “cropped a specific part of reality in the lab” and “defined their own temporality” which Schmidgen calls an artificially created present (14), a temporality extracted from the conditions of the real in order that it might be measured. Conditions that were necessary for the precise study of bodily time are now replicated in media technical temporalities which capitalise on the relatively sluggish human physiological response times measured by Helmholtz under these same conditions. The artificial temporality of an experiment that revealed the durations of perceptual signals is now reproduced by one that capitalises on precisely those durations to construct the visible in advance of perception. Digital media recreate this artificial present anew every time we press play. Between the ‘stream’ of conscious experience and the ‘streaming’ of digital media lies a concantenation of technical processes of artificial colourimetry and temporalisation.

Duration and spectrum are not directly experienced, but recreated from micro-temporal and mono-chromatic fragments, re-synthesised afresh for each viewer. How do these media re-temporalisations of ‘the live’ and ‘the present’ re-model our own temporal perception? In media environments that are optimised for the individual, where search results, adverts and content are all are tailored to our preferences, where ‘timelines’ are personalised, do we still inhabit time communally? To be con-temporary is literally to be in-time-with, but what happens to communal experience of time when we are no longer in sync with our contemporaries?

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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. 

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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.