Sometime in the first 15 minutes of Zana Briski and Ross Kauffman’s stunning “Born Into Brothels,” we’re shown footage of an interview with a young girl, no more than 10 years old. She is surrounded by filth, poverty and addiction, but seems cheerful and carefree nonetheless. She tells the filmmakers about her life in the Calcutta brothel she calls home, speaking without a trace of self pity or any visible sense that her situation is unusual.

“They ask me, ‘When are you going to join the line?'” she says, referring to the prostitutes who stand outside of the brothel, soliciting business. “They say it will not be long.” She turns her head as she finishes the sentence, throwing half her face into shadow that tinges her smile with rue.

For several years, the two filmmakers lived among the brothels of Calcutta, originally planning to document the lives of prostitutes through still photography and film. But they soon realized that they were far more enthralled by the prostitutes’ children, always underfoot and never noticed, growing up with only thin curtains between them and their mothers’ trade.

The story of these children, living in shadows, rejected by society, is compelling enough as it is. But the two filmmakers took their project from compelling to sublime when Briski came up with the idea of giving the children point-and-click cameras and basic photography lessons. Their photos are heartbreaking, amazingly upbeat glimpses of the details that delight children everywhere: Two rabbits on the street, friends striking poses, a stray dog.

The filmmakers wisely maintain this child’s-eye-view throughout the documentary. When the camera pans through crowds, it does so at the eye level of a child. More importantly, as Briski and Kauffman explore the brothels, they follow the tortuous, scampering paths of the children, trailing after the sounds of their voices. All the anecdotal details of life in the brothels come from the mouths of children, presented in the form of individual interviews, the most harrowing part of the film. The children’s stories alternate between rambling descriptions of their friends’ personality quirks and painfully pragmatic assessments of the bleakness of their lives.

“There is nothing called hope in my future,” one boy says simply when Briski asks him to tell her about his aspirations.

Briski’s background in photography makes the film as visually stunning as it is emotionally wrenching. Her shots are grainy and unfocused at just the right moments, and she uses the garish, lurid colors of the city at night to depict the harshness and depravity of the red light district. Her use of light and shadow is delicate and beautifully nuanced, and works perfectly to imbue situations with otherwise inexpressible moods. All of this is made more impressive by the fact that this is apparently Briski and Kauffman’s cinematic debut.

As the documentary progresses, Briski leaves her place behind the camera, becoming inextricably involved in the lives of the children. At first she takes them on trips to the zoo and the beach, though as years pass she becomes desperate to save them from their grim futures — particularly the girls, who in a few years’ time are slated to take their place among the working women of the brothels. To this end, Briski goes through the long and difficult process of finding the children places in boarding schools, running up against stubborn parents, bureaucratic stonewalling and society’s aversion to the children of sex workers.

The filmmakers’ successes, which includes exhibiting the children’s photographs in galleries around the world and raising money for their education, are undeniably triumphant. Yet Briski acknowledges at several points during the documentary that there is ultimately little they can do to help the children. We are forced to remember, eventually, that this is not a Hollywood film, but a documentary (in real life, all of the children will not be whisked away from the poverty in which they are so dramatically mired). Despite their vivacity, intelligence and the beauty of the art Briski helps them to create, some of the children will still follow in the footsteps of their parents, hashish addicts and prostitutes. The brothels, it seems, are difficult to escape.

Sunday, “Born Into Brothels” was awarded the Academy Award for Best Documentary Feature, an honor that the poignant, jarringly moving film well deserves.