The Nature of Blackness in Art and Visual Perception

236 seems to me, therefore, that the training of artists needs to be modified to make them aware of new aspects of nature and of technological developments that are not encountered in ordinary daily life. I have noted such a response by some of those who make computer art, which can be On the Meaning of Order (II) accounted for by the fact that they have either a scientific or a technical background. ( ~ ~ ~ ~ i ~ d 27 October 1980) Susanne Pach Eduard-Schmid Strasse 7 8000 Munich 90. Fed. Rep. Ger. THE NATURE OF BLACKNESS IN ART AND VISUAL PERCEPTION Colour television operates through a three-colour additive process in which three signals are generated in the television camera. The camera consists in effect of three cameras in one, one of the component cameras being redsensitive , one green-sensitive and one blue-sensitive. The screen of the television receiver consistsof a fine mosaicof very small red, green and blue phosphor dots that are modulated by the incoming signals to reproduce in colour the scene being transmitted. For good technical reasons, however, the signals are not transmitted as separate red, green and blue signals but as a luminance signal that contains the black-and-white information and two chrominance signals that carry the colour information. This principle can be demonstrated by preparing a colour transparency from which all the luminance contrasts in the original picture have been removed. There is no occasion here to go into the rather intricate procedure by which such a transparency can be prepared, but it involves a photographic masking technique. This transparency corresponds to the colour information carried by the chrominance signals in a television transmission. A black-and-white print of the original picture is also prepared to correspond to the black-andwhite information carried by the luminance signal in television. If, now, the ‘colour only’ slide is projected in register on the black-and-white print, the original picture is restored in its gradations of luminance and colour. Through the very helpful co-operation of R. W. G. Hunt and Paul Ward of the Research Division of Kodak Ltd., I was supplied recently with a ‘colour only’ slide and a black-and-white print taken from the well-known painting ‘The Arnolfini Marriage’ by the 15th-century Flemish artist, Jan van Eyck. The slide and print were not taken from the whole of the painting but from the upper half of the figure of the lady in the dark green dress.When the slide was projected in register on the print, the original appearance of the lady in the painting was fully restored, and it provided a very effective demonstration of the principle employed in the transmission of the colour television signals. It did more than that, however, because the colours in the ‘colour only’ slide were so unexpected that it led me into thinking more deeply about just what was happening in the demonstration. In the original painting, the lady’s hair and eyes are a fairly dark brown and her dress is a dark green, but in the ‘colour only’ slide the hair and eyes looked a light salmon pink and the dress was a light lime green. Yet when projected on the black-and-white print, the original brown and dark green colours were restored. In a sense this should not have surprised me, because the effect of projecting the slide on the print isto reduce the luminance of those areas of the slide falling on the darkerareas of the print. Examination of a colour atlas such as the Color Harmony Manual based on the Ostwald system showsthat much the same differences are seen between light and dark samples in the Hue 5 plane and in the Hue 23 plane. A further twist to the demonstration showed, however, that the effect was not just due to the reduction in luminance in the darker areas of the print. The additional stage that I introduced into the demonstration was to project the ‘colour only’ slide on to a uniform sheet of near-black paper. This reduced the luminance of the projected picture to approximately the same level as the reduction produced by the darkest...