Mr. Muniz eventually transforms their images into classical portraits, which he models in his studio with their help, using garbage they have scavenged from Gramacho. (The catadores were paid for their time and the materials.) Suellem, posing with her two children, becomes a Renaissance Madonna; with Zumbi Muniz recreates Millet’s “Sower”; and Tião sits in a bathtub like David’s Marat awash, in a sea of filthy clothes, plastic bottles and abandoned toilet seats.

By the film’s end Tião’s portrait has been sold at auction, and Mr. Muniz has donated his $50,000 take to the workers’ cooperative. And the catadores have visited the Museu de Arte Moderna in Rio to see themselves in Mr. Muniz’s 2009 retrospective. “Sometimes we see ourselves as so small,” one tells reporters at the opening, “but people out there see us as so big, so beautiful.”

Mr. Muniz has also acknowledged that with a twist of fortune he might have become a catador himself. “They just weren’t born very lucky,” he says in the film. “But we’re going to change that.”

Yet his own stars seem to have been remarkably well aligned. Although he grew up in a poor family in São Paulo, his habit of expressing himself with tiny hieroglyphic drawings won him a scholarship to an art school. At 18, buoyed by an intense fascination with perception and optics, he talked himself into a job with a billboard company and became something of an advertising wunderkind.

That career ended abruptly when he was shot in the leg on his way to his first black-tie gala. His assailant, to ensure that he didn’t press charges, offered him cash. Mr. Muniz took the money and decided to try his luck in America.

By 1983 he was in New York, working as a framer and living in the East Village while its gallery scene was booming. When he happened across Jeff Koons’s enigmatic vacuum cleaner and basketball sculptures at International With Monument, he said: “I realized that I could be an artist too. He was speaking my language.”

A friend lent him a studio space, and Mr. Muniz began making his own objects, like a shiny shelf intended to gather dust, or a pre-Colombian drip coffee maker. In 1988 he had his first New York solo gallery show. Then he began experimenting with drawing and photography.

On a 1996 trip to St. Kitts he discovered the perfect blend of all three mediums when he befriended some families at a sugar plantation and took Polaroids of them. Back in New York, he tried to figure out what made the children look so luminous while their parents seemed so broken down. After realizing the difference was a lifetime spent working with sugar, he used the glittering grains to draw and form the children’s portraits on black paper, and photographed the results. The Museum of Modern Art chose them for its 1997 “New Photography” roundup, and Mr. Muniz’s career as a photographer was born.

“He was always interested in visual theory and the vernacular,” said Brent Sikkema, his dealer. “But this was a defining moment.”

The work’s accessibility often leads art cognoscenti to dismiss Mr. Muniz, said Peter Boswell, a curator at the Miami Art Museum who organized “Vik Muniz: Reflex,” a 2006 retrospective there. (It toured the United States, Canada and Mexico for two years, then went to Brazil in expanded form; it closed in August.) “Because Vik is so prolific, some people are tempted to write him off,” Mr. Boswell said. “Even at the beginning, people were saying that it was just clever work that didn’t have substance. But I think people who say that aren’t looking very deeply. Vik’s got a whole lot of substance, both within the work and behind the work, in the whole machinery that he has put into place.”

And it’s increasingly clear that Mr. Muniz has ambitions beyond the art world — something to do with alchemical transformation, not just of garbage into art, and art into cash, but also of people’s lives.

In this he has been successful. Since the film wrapped, some of the catadores have found new jobs, and Mr. Muniz and the filmmakers have donated $276,000 to the cooperative, Mr. Ghivelder said, which has been used, among other things, to buy a truck and computers, found a library, provide capital funds for the organization and finance a small-business training program. (Another $50,000 from Mr. Muniz went to the catadores who posed for portraits.)

The project also seems to have changed Mr. Muniz’s perspective on imagery. “The really magical things are the ones that happen right in front of you,” he said. “A lot of the time you keep looking for beauty, but it is already there. And if you look with a bit more intention, you see it.”