Look at any constellation up in the night sky. Some stars will be shining more brightly than others. I am standing in a sepulchrally long and dark gallery when that thought occurs to me, staring up at a new photographic installation by Mat Collishaw. Images of grievously wounded children are flashing momentarily on all four walls and, just as quickly, fading away again. The walls themselves are covered with phosphorescent paint, hence the eerie, haunting effects.
This is Collishaw's first big London show in five years. He belongs to the YBA generation that graduated from Goldsmiths College in the late 1980s, taking part in the "Freeze" exhibition that launched the group. The piece he displayed in that show, a deeply disturbing image called Bullet Hole, is still his best-known work. It is a close-up of a bullet wound, enriched, enlarged and thoroughly aestheticised. Damien Hirst is still a close friend. Tracey Emin is a former girlfriend. Why has he not enjoyed a similar degree of recognition? Why has his star not shone as brightly as others'? Is it something to do with an inability to be a relentless self-publicist?
The new show, together with an exhibition at Haunch of Venison this summer, may help to change all that. Collishaw's new installation is a bravura manipulation of the photographic image, played across all four walls of this long and fairly narrow gallery space, which feels, as you pace back and forth along it, the slightly uneven parquet floor squeaking beneath your heels as you go, a little like a courtroom. And that seems about right, because this show is all about moral issues - the prurience we feel before images of violence. The aestheticisation of violence. The subject has a long history in western art: were not Raphael and Ribera aestheticising violence when they showed us such exquisite devotional images of Jesus on the cross? Was not the horror eased away by such images of beauty?
For this installation, Collishaw has taken images of violence from the popular press, of violence perpetrated against children. The starting point for the entire project was the grisly school siege in Beslan, southern Russia, which went on for three terrible days in 2004. The artist has chosen images from that siege, and from other sources, manipulated them and projected them on to walls. But it is the manner of the projection, and what happens to those images, which is so enthralling in this show.
Each image flashes on to the black wall, but it does not disappear. Instead, it begins to fade into a kind of ghostly after-image (or perhaps after-memory) of itself. Then, bang, another image gets projected somewhere else, quite at random, with the same intensity, and that also begins to fade, so that we are left with this ghostly layering - or near-layering - of images of terrible violence. In spite of all we know, they begin to look heroic, if not iconic, projected and lingering like this, as if they were memories of some image from Blake, Goya or Géricault. We even seem to feel that we are beginning to recognise how they are almost mimicking details of famous paintings. In short, we heroicise them. They begin to assume the status of Fine Art. How morally dubious.
"The thing about the Beslan siege is that it was a three-day spectacle," Collishaw tells me a little later, when I emerge from the heart of all that darkness. "The photographers could dig in. They could really prepare themselves, so that when the child ran screaming, wounded, out of the schoolroom, pop . . ." He gives the tabletop a small, tight smile. "And there we have it, the perfect picture, beamed around the globe in minutes, in order to satiate our seemingly insatiable appetites for such terrible things." I remind him that he is no better than the others - the proof is downstairs. He accuses the press of behaving immorally by taking beautiful photographs of maimed children, but he himself has first manipulated and then raised some of these very images for our delectation downstairs, to such an extent that we admire them, even find them beautiful. Isn't all this highly questionable?
He looks thoughtful, this 42-year-old man from Nottingham, sitting there in his floral shirt open almost to the waist. Is that a crucifix hanging from a cord tucked inside that shirt? I can't quite see. He strokes his chin, preparing his words. "Yes, I wanted to make them iconic in some way, and it may be morally dubious. The human body is primed to respond in some heightened way to images of crimes: the adrenalin starts to pump. And, yes, it does appeal to some prurient part of me. But didn't Géricault do the same thing in his great painting The Raft of the Medusa? That horrifying painting had its starting point in the images from a newspaper story . . . It is also true that I wanted to draw attention to the terrible, primitive poignancy of an adult carrying the body of a maimed child."
There is a second part to this show. A row of daguerreotypes, framed behind Plexiglas, is mounted in small leather cases, left open to expose the image on the right. They are all pocked and tarnished-looking, as even the finest of daguerreotypes tend to be. On the left, the inside of the lid of the box is lined with red velvet to protect the image when the lid is closed.
I look again at these sad photographs of helpless, wounded children. Turning the images into daguerreotypes - a costly and enormously time-consuming process - seems to have set the children back by about a hundred and fifty years. These could have been helpless victims of the Paris Commune. Photographic images of human misery can be made to look so timeless, if you know how.
"Deliverance" is at Spring Projects, London NW5, until 22 May.