sean cubitt • donau-krems

Archaeology of screens

Attributed to Albrecht Dürer, 1488, woodcut, “The Pilgrim”3

Albrecht Dürer, intaglio print, The Kinight, Death and the Devil, 1514

Young Woman Holding a Candle in a BedchamberNicholaas Verkolje (Dutch, 1673–1746) after Godfried Schalcken (Dutch, 1643–1706)Published by Gerard Valck (Dutch, 1651/2–1726)Mezzotint; Image: 10 5/8 x 9 in. (29 x 23.4 cm)

Credited to the English Prince Rupert, ex-iled as a result of the English Civil War, in the late 1650s, mezzotint is a process for pre-paring engravers' plates by use of a rocker whose surface is spiked with emery or other textures sharp enough to pierce the wax. By rocking into the surface, the plate acquires a mass of pittings sufficient to hold ink which, when printed, produce surfaces of vary-ing densities of dots and scars. Pressure, duration and direction of rocking the tool produce a variety of effects from a scarcely visible tone to near-black areas. This ground of tiny marks which hold the ink can then be 'scraped', burnished to stop the ink holding, so reversing the familiar process by which engravers and etchers moved from light to dark. The plate can then be treated with en-graving, etching or drypoint to add further effects. While producing remarkable effects of light and darkness, mezzotint is notorious-ly difficult to ink, and the shallow markings on the plates are soon worn

THE GRID

Goya - El sueño de la razón, (The Sleep of Reason Produces Monsters), from Los Caprichos 1799 (detail)

A very similar effect is secured by a different method, introduced to Europe around 1768 and often ascribed to Jean-Baptiste Le Prince, aquatints, the me-dium much favoured by Goya. Here the ground is prepared by dusting it with rosin which is heated to make it bond to the plate. Then the plate is bathed in acid, which etches tiny circles around the grains of rosin, creating teeth which will hold ink. Areas of the plate that are to remain blank can be treated with tar or varnish, which protects that area from the rosin dust. The result is a fine textured ground whose ink-holding capacity is a function of the strength of the acid and the duration of the bath. The acid may be painted onto the plate in the process known as spit-biting, to limit the textured surface to restricted zones on the plate, In a variation, the tinted areas can be rubbed with soap, which is acid-resistant but tends to bubble, so creating visibly uneven textures.

Richard Parkes Bonington (1802-1828) Tour du gros horloge, Évreux Lithograph, 331mm x 245mm(detail of clockface on next page)

Lithography works on the principle of the mu-tual repulsion of grease and water. Originally working on stone (whence the etymology, from the Greek lithos, stone), specifically a particu-lar Bavarian limestone, the artist drew with a greasy crayon, then wet the surface. A greasy ink would then adhere to the marked areas but be repelled by the water, and paper could then be printed from the ink sticking to the drawn parts. From the 1830s zinc plates substituted for the stone, which became increasingly rare, and from the 1890s aluminium sheets were used. Modern lithography adds another process: af-ter drawing, the plate is washed ('etched') with an emulsion of gum arabic in dilute nitric acid to fill the undrawn areas of the plate, the origi-nal drawing is removed with lithographer's tur-pentine, leaving a salt layer deposited by the etching materials which attracts water, which in turn repels the ink, which is trapped in the unsalted, originally drawn areas.

I find that Seagull Grade 4 gives me a better print of my Frozen Lake and Cliffs than I was ever able to get on Agfa Brevita Grade 6, and the tone is magnificent. This is one of those significant early negatives (c. 1932) that must be considered quite poor in quality and very difficult to print. The negative contains enough information to yield an acceptable print with great effort, and I continue to improve the 'salvage' printing as best I can (Adams 1983: 50).

It was his practice, when conditions allowed or demanded, to use a spot meter, an exposure meter callibrated to sample light from a one de-gree arc (as opposed to the 20 or 30 degrees of arc of a normal exposure meter). The spot meter could be placed much closer to objects than the camera to get a specific sample of the light. The apparent value of light is as much a product of mental activity as of perception: the brain compensates for light-levels, seeing a white sheet of paper as 'white' regardless of whether it is in shade or full sun. Cameras do not have such equilibrating brains, and 'see' only what is there before them. The spot meter disregards the eye'-brain system, and instead emulates the reac-tion of the correspondingly small area of the exposed film. rather like the way Impressionist painters ignored their learned habits of colour and applied themselves to seeing and copying the colour in fragments of the scene in front of them, the spot meter ignores everything about the scene to be imaged except the value of the light immediately in front of it, abstracting from it a measurement of brightness.

William Henry Fox Talbot, Latticed Window at Lacock Abbey, photogra-vure, 1835

William Henry Fox Talbot: Samples of Lace, 1839

Stephen H. Horgan, Steinway Hall, New York Daily Graphic, December 2, 1873: first prited halftone photograph.

when in 1855 Alphonse Louis Poitevin discovered that bichromated yellow gelatine reacted to light by hard-ening, the way was open for large-scale printing from individual photographs and their truly mass circulation embedded in print media like magazines. Relief print-ing methods involved exposing the gelatine (and sub-stitutes including treated albumen and fish glue) to the negative, etching out the unexposed areas and inking the raised surfaces. The halftone process interposes a screen between the original and a new photograph of it, giving the effect of a grid of dots of varying size, depending on the depth of the tone. This process adds more tonal variation, although to get good greys re-quires such fine dots that they can only print to the best chalk-faced art paper, whence the relative crudity of newspaper reproductions compared to those in expen-sive magazines and books. (Indeed visible grain re-mains a major signifier of factual status, for example in images drawn from CCTV or paparazzi telephoto snaps of celebrities). Early screens were made of woven tex-tiles, and had some of the roughness of mezzotint: rapid industrialisation lead to the use of finely-lined glass plates, which organised the dots into regular rectilin-ear grids, in part to help them work with transmission technologies.

Bell Labs Wirephoto, first commercial transmission, New York 1935

John Logie Baird, experimental 23-line vertical scan television transmission 1927, featuring Stooky Bill. 1993 reconstruction by David Hall.

Baird Televisor, schematic and demonstration prototype,

The Quatermass Experiment, BBC TV, 1953, dir Rudolph Cartier, scr Nigel Kneale

Cathode Ray Tube

Trinitron Mask

LCD sub-pixel

Digital light projection

DMD Digital Micromirror device

uncompressed series of frames

same series showing selected chang-ing areas to be transmitted between keyframes

keyframe keyframeblocks / macroblocks/GoBs

How Codecs Work

The resolution of each chroma component in a macroblock (Cr and Cb) is half that of the luminance (luma) compo-nent. Each chroma block is partitioned in the same way as the luma component, except that the partition sizes have exactly half the horizontal and vertical resolution (an 8x16 partition in luma corresponds to a 4x8 partition in chroma; an 8x4 partition in luma corresponds to 4x2 in chroma; and so on). The horizontal and vertical components of each mo-tion vector (one per partition) are halved when applied to the chroma blocks. Example: Figure 2-3 shows a residual frame (without mo-tion compensation). The AVC reference encoder selects the “best” partition size for each part of the frame, i.e. the partition size that minimizes the coded residual and motion vectors. The macroblock partitions chosen for each area are shown superimposed on the residual frame. In areas where there is little change between the frames (residual appears grey), a 16x16 partition is chosen; in areas of de-tailed motion (residual appears black or white), smaller partitions are more efficient.

Iain E G Richardson, (2003), H.264 / MPEG-4 Part 10 White Paper : Prediction of Inter Macroblocks in P-slices

Vector Prediction

genealogy of screen technologies

DLP trinitron mask

cathode ray tube

drum scanner

wireleles photo

half-tonephoto

printing

lithographyaquatintmezzotintetching(intaglio)woodcut

archaeology of screen technologies

DLP trinitron mask

cathode ray tube

drum scanner wireless

photo

half-tonephoto

printing

lithographyaquatintmezzotintetching(intaglio)woodcut

silk-screen(serigraphy)Linocut

jacquardloom

difference engine

Memento Mori, Guiseppe. Part of a bound collection of Italian (reverse image) copperplate engravings, Italy, c. 1700. © Collection Werner Nekes

typing pool

Ø

For Miller, the non-identical zero is not just an analogy: it is the excluded figure that speaks and is spoken to in logical discourse. The subject both exists and does not exist, just as zero is represented by one (or indeed, as he puns, by the symbol ø, the empty set). In Lacan, lan-guage is representation. What is represented is not pre-sent in language, but only re-presented. The subject is no exception: it is only presented, never present. The sub-ject is absent from language: as a kind of zero, by anal-ogy with Miller’s argument about logic, its exclusion actually causes language. The purpose of language is to speak the subject which started it”, each new signi-fier adding another ‘plus 1’ to the chain in an attempt to control, and perhaps to conclude the attempt to make the subject whole again. This leads Lacan to argue, in a phrase repeated by almost all the authors involved in suture theory, ‘a signifier represents a subject for an-other signifier’. This, as Heath is at pains to describe, is the obverse of the more familiar statement ‘a signi-fier represents something for a subject’. As an effect of language, the ‘something’ that is represented by a sig-nifier is the subject to whom it is addressed. Therefore the subject is present in language after all. For Miller this contradictory condition is the basis of suture: a flickering in and out of existence which is managed through the succession of signifiers in the unfolding of language.

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