John Berger persuasively declared the portrait dead, or at best hollowed out, as a painting format more than 50 years ago. He believed it had devolved in modern times to mere affirmation of the sitter's social position. But since then, artists as diverse as Lucian Freud, Alex Katz, Cindy Sherman and George Condo have shown that enough oddity and ambiguity remain in the portrait as a pictorial and conceptual construct to keep it alive as a vehicle of creative ambition.

Los Angeles painter Ray Turner works in the wake of this controversy and of the recent predecessors who have kept it going. His paintings on glass at Toomey Tourell - all portraits - display a sort of grotesque fluency. Even as they form convincing likenesses, they confront us touch by touch with the unlikeness of paint to the fugitive focal points by which we recognize a person in a face.

Turner works with a confidence and material opulence that can bring London painter Frank Auerbach to mind. But where Auerbach deliberately evokes the expressionist lineage in modern European painting, Turner's work smacks more of the lucky strokes of the self-taught sign painter. His portrait of his son "My Little Fish" - one of many in the show - looks less descriptive the more you bear down on it. Under scrutiny, it turns from a likeness into a scowling of paint itself, as if Turner had sought not resemblance but the mask-like qualities of his medium.

But what a painting: a writhing of brushstrokes, all green tones, that somehow approximates a face shadowed in sunlight, and an image that gives the feeling of an accurate report. The impermeable glass pane leaves the paint standing on it, casting shallow shadows and heightening the strangeness of the portrait's bid for realism. In other pictures, Turner toys with paint's fluctuating suggestions of makeup, skin condition, light and shade.

His more literal efforts are impressive in more conventional terms, as openly stylized portrayals. But the few pictures such as "My Little Fish" that look as if they have formed themselves strike a much deeper echo in the viewer: the feeling we all have sometimes of being represented by a face we have not chosen, despite all we do to promote its correspondence to our inward selves.

Ken Baker San Francisco Chronicle