The German photogapher Thomas Ruff, however, like many of his contemporaries, has chosen to use the medium as an anti-representation of reality. Playing games with the established notion of photography's objectivity, he produces images - candid takes of buildings, interiors or people - that at first glance seem firmly embedded in the tradition of the Neue Sachlichkeit, or "new objectivity", beloved of his compatriots since August Sander laid its foundations in the 1920s. But they are images which, at a second glance, begin instead to reveal the artificiality of the medium. Look at the series of pictures on the right: what initially appear to be straight portraits have been manipulated so you are met each time by the same hard blue gaze.
The images shown here are an addendum to Ruff's first outing into portraiture. For a major project in the mid-1980s, he created a long series of head- shots, mostly of his contemporaries - people he knew well or saw often in the corridors of the art academy in Dusseldorf. At first he let his subjects select a coloured background, as if giving them some say in how they would be represented (although the range of shades - sickly lilac, maybe, or a nasty orange - was fairly unlikely to include anyone's real hue of choice). Later he abandoned even that pretence for a plain, pale, value-free backcloth.
Making reference to the archetype of the passport photo, his sitters faced the camera unsmiling and uncomfortable, gaze fixed firmly in middle distance. They called to mind the immobilised look we adopt in anticipation of the flash exploding in the photo booth and the way our features harden as the four consecutive light bombs strike us between the eyes. This is the firm-jawed expression of vacancy with which we try to depersonalise ourselves for the purposes of bureaucracy while trying simultaneously not to blink.
Faced with that series of head-on, indentically framed faces, everything that the portrait stood for in the long tradition of Western art fell apart. You came to them looking for personal histories, for narratives, for clues in facial expressions that spoke of the particularity of the individual, for entertainment even. What you found was an inflexible visual formula that obliterated the sitter's individuality. You think that every picture tells a story? In Ruff's world, those days are gone.
Another set of images intruded right to the heart of the documentary world as Ruff set about re-photographing grainy black-and-white pictures that he had been saving from newspapers since the early 1980s. Enlarged, mounted, framed and hung like art works (though devoid of dates or titles) on the gallery wall, pictures originally produced as definitive bringers of factual information were aestheticised by Ruff's treatment. Their news content - whether it was of a politician, or a disaster, or a triumphant moment - was eclipsed by their reincarnation as art objects in their own right.
Ruff would have it that images are all surface and no depth. "I work on the basis that a photograph can't represent a person or a character, that a person has too many layers to be depicted in a photograph," he says. "A photograph of a person is just one of a million possible photographs of that person. I don't believe in the psychologising portrait photography that my colleagues do, trying to capture the character with a lot of light and shade. That's absolutely suspect to me."
More suspect still to a French art critic was what Ruff's portraits implied. "He wrote that they were either to do with Nazism or Social Democracy. Of course, they are in support of neither. But I responded to his criticism by producing the ultimate set of Aryan images. I chose 12 of the existing pictures from the original portrait project and coloured the eyes blue on the computer."
The "blue-eyed" series, now published in a new anthology of contemporary photography, called Surface, makes absolutely clear how Ruff's work is an exercise not in representing any truth but in stripping it away. It also suggests how effectively photography, like political propaganda, can sell false truths. Far from the idealisation or fascination with the individual subject we have come to expect of a portrait, these pictures talk more of the relentless uniformity with which contemporary media presents and represents its subjects, and the chilling power of photography to manipulate and control.
'Surface: Contemporary Photographic Practice`, edited by Michael Mack, is published by Booth-Clibborn Editions on 27 May, priced pounds 38.