New York ? Richard Avedon, the revolutionary photographer who redefined fashion photography as an art form while achieving critical acclaim through his stark black-and-white portraits of the powerful and celebrated, died Friday. He was 81.

Avedon suffered a brain hemorrhage last month while on assignment in San Antonio, Texas, for The New Yorker, taking pictures for a piece called “On Democracy.” He spent months on the project, shooting politicians, delegates and citizens from around the country.

He died at Methodist Hospital in San Antonio, said Perri Dorset, a spokeswoman for the magazine.

“We’ve lost one of the great visual imaginations of the last half-century,” said David Remnick, editor of The New Yorker.

Avedon’s influence on photography was immense, and his sensuous fashion work helped create the era of supermodels such as Naomi Campbell and Cindy Crawford. But Avedon went in another direction with his portrait work, shooting unsparing and often unflattering shots of subjects from Marilyn Monroe to Michael Moore.

“The results can be pitiless,” Time magazine critic Richard Lacayo once noted. “With every wrinkle and sag set out in high relief, even the mightiest plutocrat seems just one more dwindling mortal.”

As a Publishers Weekly review once noted, Avedon helped create the cachet of celebrity — if he took someone’s picture, they must be famous. His fun-loving, fantasy-inspiring approach helped turn the fashion industry into a multibillion-dollar business.

Scores of imitators struggled to replicate his signature style, known simply as “The Avedon Look.”

“The world’s most famous photographer,” trumpeted a 2002 story on Avedon in The New York Times. It was a title he wore for decades; back in 1958, he was named one of the world’s 10 finest photographers by Popular Photography magazine.

Richard Avedon is photographed in front of his self-portraits, part of the exhibit Richard

Prestigious institutions as the Metropolitan Museum of Art in New York City and the National Gallery of Art in Washington, D.C., staged major Avedon retrospectives, and his list of honors stretched across more than 50 years. In 2003, he received a National Arts Award for lifetime achievement.

During his career, Avedon worked for such photograph-driven publications as Vogue and Harper’s Bazaar, and served as The New Yorker’s first staff photographer.

“He’s the most wonderful man in the business because he realizes that models are not just coat hangers,” famed model Suzy Parker once said. An Avedon shot of Parker from 1959 was credited with igniting the bikini boom.

Avedon said his view of the world was literally affected by his nearsightedness. “I began trying to create an out-of-focus world — a heightened reality better than real, that suggests, rather than tells you,” he once told The New Yorker in an interview.