Mark O'Kelly's In Fashion at the Limerick City Gallery is the largest exhibition of his work to date. It's also a good survey of his output, which is both highly particular and highly diverse, and often puzzling in terms of its underlying rationale.

It's puzzling because, though for the most part very precisely representational, O'Kelly stands back from his imagery, which is drawn from various second-hand sources, notably including photographs reproduced in newspapers, magazines or brochures. His paintings are presented as though they are forensic documents, evidence of something, but the something remains undefined.

There are consistencies of imagery, including cities, either in terms of intricately detailed panoramas or closer views of communal spaces, both exteriors and interiors, and, more recently, scenes from the world of couture. One room of the show is given over to a series of paintings that could be described as abstract. But they are not abstract paintings in the normal sense of term. Certainly in the context of O'Kelly's work they are no more abstract than his most overtly representational paintings.

This is, again, because he is at least one remove from his imagery, something that applies to the ostensibly abstract paintings as well. Rather than being abstract compositions per se, they are representations of abstraction. More, they are investigations of abstraction in terms of a number of its signature styles. One of those styles is that of Brice Marden. O'Kelly recreates Marden's characteristic overlapping loops of colour. The significant difference is that, while the physical gestures of Marden's brush strokes literally constitute the image - they are the image - O'Kelly makes a representation of the brush strokes.

When we look at the gestural marks in his painting, it is clear that he is absent from the gesture in a way that Marden isn't. What he makes is studied and removed, remote from the spontaneity of Marden. If there is a critique implied in what he does here, it is not so much of spontaneity as it is of style, particularly signature style, by which abstraction becomes a way of branding and commodifying an individual identity. So we can conclude that he distrusts the notion of style.

One of the abstracts is an intricate linear network titled Comb from 1998. This very spare painting is important in the context of O'Kelly's work since. The comb could well be a honeycomb, symbolic of any modular, orderly system.

Such systems are what we find again and again in his views of the city. Modernist blocks make up landscapes of grid-like structures. There are, incidentally, many beautifully painted images of buildings throughout the show. Jenoptik is a striking example.

The individual blocks come across as formidable pieces of design, but the order and rationality that they exemplify begins to fray the wider the scope of a particular image. It's as if the buildings are islands of rationality, collectively making up archipelagos of rationality in wider, wilder spaces. There is a recurrent emphasis on the edges of things, the boundaries where order meets chaos or, figuratively perhaps, where culture meets nature. In Kandalama the clean geometric lines of a contemporary building angle into an enveloping mass of vegetation. The frenetically ordered Johannesburg fades into a limitless hinterland. The meticulously mapped Forest eludes containment, seeming to extend indefinitely beyond the pictorial boundary.

But disorder and chaos intrude in other ways as well. The disciplined blandness of the urban environment is underscored by anxiety in Car and Car and Bridge, both of which hint at disturbing narrative possibilities. Even more pointedly, the apparent coherence of O'Kelly's images tends to disintegrate on closer examination. He works from processed imagery, and relishes the distortions and signs of interference that accrue along the way. Quite dramatically, features like faces that look coherent from a metre or two back dissolve into a jumble of abstract markings if you look closely.

The implication of Audience, which is a picture of an audience, is that audiences are there to be seen, to be looked at, a neat inversion of the ostensible order by which they are there to look at something else. It's undeniably true that in many cases audience members are there to be seen, for social and related reasons. This is underlined in O'Kelly's view of an audience at a fashion show. Celebrities are routinely paid to attend high profile shows, thus bolstering and perpetuating the status of couture culture.

In any case, the high visibility audience is ostensibly there to look at clothes. A series of frontal views of models on the catwalk emphasises the schematic, constructed nature of the garments, the way they are compositions built over the armature of the body. The body is treated as a kind of abstraction, as the studied blankness of expression on the part of the individual models suggests. Some gestural face painting and indeed the title Yohji evoke tribal ritual, and the single-person views of models titled according to the designer whose clothes they wear, have a totemic quality about them.

O'Kelly doesn't come across as a moralist, and there is no sign that he is setting about disparaging the fashion world. Both cities and the world of couture are artefacts.

Fashion is an area in which questions of representation, perception, status and innovation are concentrated. In terms of his interest, the fashion world could well be the art world. Everything he represents about fashion is already representation. A similar point comes across in his Two Stylists from 2000.

In an image that looks as if it was sourced in any one of thousands of glossy style magazines, his two stylists are manifestly styled to the nth degree. They are all artifice. Every aspect of their appearance, even their physical attitudes and their setting, is carefully calculated and constructed. They are all image. In fact, all of O'Kelly's paintings begin with a pre-existing image of one sort or another. His examination of these images brings into play ideas of order and chaos, culture and nature. His work is not simple or straightforward, but it is engrossing and rewarding. At heart, perhaps, more than anything, it's about looking.

Mark O'Kelly's In Fashion is at Limerick City Gallery of Art until February 27th