Icons, before they can become iconic, require images - "images" in both senses of the word - and there is no more iconic American artist than Georgia O'Keeffe. The photographic rendering, and enhancement, of her fame is the subject of the Portland Museum of Art's highly satisfying "Georgia O'Keeffe and the Camera: The Art of Identity."

The most obvious element in O'Keeffe's hold on the popular imagination is, of course, her art: the way it draws on both abstraction and representation; the luxuriant sobriety of its style, with a palette balancing intensity and restraint; and the capacity it has to simultaneously locate and universalize the desert Southwest.

It's a mark of how comprehensively, as well as astutely, "Georgia O'Keeffe and the Camera" has been put together that it includes 18 works by her as well as more than 60 photographs of the artist or her surroundings.

Yet what helped make Georgia O'Keeffe the almost-totemic figure she became is not just her talent. American art can claim painters with great popular appeal whose work is either as impressive as O'Keeffe's (Winslow Homer, Edward Hopper) or as recognizable (Norman Rockwell, Andrew Wyeth).

None boasts her iconic status.

In part, that's owing to O'Keeffe's role as a symbol of female strength, independence, and achievement. More than that, it's our knowledge and appreciation of not just the appearance of her art but her own appearance.

Her one real artistic counterpart, in this respect if no other, is Andy Warhol.

As it happens, Warhol is one of the many photographers who took O'Keeffe's portrait. They include some of the best-known in the medium's history: Ansel Adams, Irving Penn, Eliot Porter, Arnold Newman, Cecil Beaton, Philippe Halsman, Yousuf Karsh.

Supremely, there was Alfred Stieglitz, American photography's patriarch and chief impresario. He was also O'Keeffe's husband and took more than 350 photographs of her between 1917 and 1937, a unique rendering over time of one major artist by another.

"His idea of a portrait was not just one picture," O'Keeffe said of Stieglitz. "His dream was to start with a child at birth and photograph that child in all of its activities as it grew to be a person on throughout its adult life. As a portrait it would be a photographic diary." The show has 13 Stieglitz images of O'Keeffe or her work. Although that might seem like a relatively meager selection, it makes good sense in terms of the larger trajectory of O'Keeffe's career. When Stieglitz stopped photographing her, she still had a half century left to live.

By itself, Stieglitz's body of work makes the study of O'Keeffe's relationship to the camera a very rich one. It comprises a remarkable emotional archive - leave aside its artistry - of love, desire, respect, rivalry, humor, affection, and something like awe. Take into account the examples from these other photographers, as well as instances from such gifted, if lesser, practitioners as Laura Gilpin, John Loengard, and Todd Webb, and the study of O'Keeffe and photography becomes not so much rich as overwhelming.

Among 20th-century painters, only Picasso - that other implacable nonagenarian - had a more complicated relationship with the camera.

Which makes Webb's "O'Keeffe Photographing the Chama River, N.M.," all the more startling an image. There she is for a change on the other side of the camera, pointing and clicking. Stetson planted atop her head, she's like a gunslinger who's substituted Polaroid for Colt.

To be sure, gunslingers rarely wore skirts, as O'Keeffe does in Webb's picture. The comparison works pretty well otherwise. In almost all these photographs, we see a formidable woman of enormous self-control - certainly, not one to be trifled with.

Handsome rather than beautiful, O'Keeffe had a face - grave, stalwart, hawky - that mocked mere prettiness. Her narrow eyes and long, flat cheeks gave her a slightly mannish look, one that makes the unblinking carnality of the Stieglitz nudes seem almost eruptive.

None of the nudes is in the Portland show (there is an O'Keeffe watercolor of a nude). It's a canny omission. Here they'd be disruptive as well as eruptive. The enduring O'Keeffe sexiness has to do with her art - even if, thanks in part to Stieglitz, that sexiness can be exaggerated. As one might expect from a smitten lover (let alone a smitten lover more than two decades older than his beloved), he imbued his early portraits of both O'Keeffe and her work with an ardent sexuality that would color subsequent interpretations of her painting.

These very first photographs crucially shaped how O'Keeffe's artistic identity would be understood. They initiated the evolution of a reputation, an evolution that would ultimately transform a daughter of Wisconsin into a kind of aesthetic madonna of the desert. The presence of many more Stieglitzes, not mention of the nudes, would inevitably shift the weight of the show away from O'Keeffe's later years. So much of the fascination here comes from seeing the subtle distinctions among the New Mexican portraits.

Adams shows a tough, downhome O'Keeffe. The Life photographer George Daniell makes her look like Francois Mitterand's older sister (it's the eyes). Both Karsh and Newman position her beneath a set of antlers, but the latter's portrait is so much more successful for being outdoors and alert to the landscape.

Then there's Warhol's 1979 screenprint, which uses diamond dust and a black background to situate O'Keeffe in an altogether different, if highly apposite context: that of celebrity. Next to the print is a page from a Q&A with O'Keeffe and her companion, Juan Hamilton, that ran in Warhol's magazine, Interview. "I like the way the waiter calls you 'Miss O'Keeffe,"' Andy gushes, "It's so glamorous."

Of course the waiter calls her that. Of course it's glamorous that he does so. And of course Andy gushes (that's the real tip-off). How could it be otherwise? As "Georgia O'Keeffe and the Camera" so thoroughly bears out, she long ago had become a star.

© Copyright 2008, New York Times Syndicate