Photographer Frank DiPerna's color images of the American Southwest and Mexican deserts are apt to leave your mouth dry.

Parched and windless, they are also preternaturally stilled by an intense midday light that leaves them nearly shadowless, distilled out of real time. He uses no tricks: "I want to be as pure as possible, and to reveal the intense natural beauty of this landscape without making it look like pretty picture postcards," says DiPerna, who heads the Corcoran School's photography department. "There's a big difference between what's pretty and what's beautiful."

As a color photographer, he has here posed himself the difficult task of finding beauty in landscapes where nature has used color with such restraint. But he has surely found -- and transmitted -- beauty in these images of sand, earth, sky and mountains. The colors he has unearthed are infinitely subtle: the dusty green of desert grass and plants, the delicate pink of furrowed soil in Oaxaca, the tender mauve and ocher strata of the high mounds in Petrified Forest National Park in Arizona.

There is much more to DiPerna's art than color, but this suite of work is an especially good example of how meaningful and expressive color can be in the hands of a photographer who knows how to use it. He also has an eye for drama (such as the ominous crack that runs through a maguey field) and for the happy natural accident of a circle of water hyacinths observed in Jalisco.

And there is the wit, the toying with scale for purposes of fooling the eye, which DiPerna did often in work predating this four-year-long involvement with landscape. The evidence: two gray, mountainous images hung together on the front wall. Apparently two views of the same place, they turn out to be very different. One is a mountain in Death Valley, the other a gravel heap in Rockville. DiPerna's show will continue at Kathleen Ewing, 1609 Connecticut Ave. NW, through Dec. 12 -- close enough to Christmas to make the crass but not irrelevant point that his art is a steal. Hours are Wednesdays through Saturdays, noon to 6 p.m.