New York art dealer Leo Castelli had it.

So did museum founders Henry Walters and Duncan Phillips.

And both of Baltimore's Cone sisters, Etta and Claribel, had it, too.

It's an "eye," of course: a combination of intuition, sensibility, training and personal experience that allows art lovers to spot a work of quality.

And if you've ever doubted the utility of a good eye in appreciating contemporary art, a visit to the current show at Gallery International ought to convince you there's still a place for this time-honored faculty.

Gallery owner Hai-ou Hou has created a show of visual conundrums by bringing together some 50 works by two dozen international artists. In this lovely exhibition, the most diverse tendencies from half a dozen or more nations are united by her discerning curatorial eye.

Take, for example, the mysterious paintings of Spanish artist Jordi Fulla, whose photo-realistic images of earth and sky evoke the high-tech precision of satellite photography as well as the surrealism of Dali and Miro.

Many observers have noted the peculiar affinity between photography and surrealism, both of which strive to present a heightened, psychologically charged expression of ordinary experience (there is even an argument to be made that every photograph, no matter how banal, inherently partakes of the surreal).

Fulla's paintings mimic the flawless surfaces of photographs, but they also confront the viewer with all sorts of bizarre and improbable juxtapositions - polished black spheres levitating amid white banks of clouds, concentric circles impressed on landscapes like the grids of a polar projection map - that recall Dali's famous melting watches and vaulting tesseracts.

On first glance, many viewers may easily conclude that these are computer-generated images produced by digital printing processes.

The realization that they are painted pictures - acrylic on canvas - transforms them into ironic visual metaphors for the ever-shifting relationship between painting and the modern arts of mechanical reproduction.

By contrast, Erwin Olaf, also Spanish, creates photographs that mimic paintings - in this case, the famous European cave paintings of Paleolithic and Neolithic times.

The twist here is that the boldly articulated figures that seem to stand or stride across the rough, rocky surface are in reality nothing more than bird-droppings that have landed on the stones and splattered into vaguely anthropomorphic shapes.

Because we're familiar with the paintings from the caves of Lascaux, we "see" these figures as artful representations - they look like the photographs we have seen of prehistoric paintings. So the artist has very cleverly used the camera to trick our eye.

There are many other examples of such exquisite visual irony in this show, including Cecilia Miguez's stunning bronze sculptures, Rebecca Szeto's flexible mixed-media collages and Peter Stanfield's quirky but oddly absorbing aluminum light boxes.

This is a show one can attend for the sheer delight of seeing - if along the way it also rekindles your faith in the ultimate authority of the "eye," all the better.

The show runs through the end of December. Gallery International is at 523 N. Charles St. Hours are Tuesday-Saturday from noon to 5 p.m. and by appointment. Call 410-230-0561.