Both inspiring and ineffably sad, Ross Kauffman and Zana Briski's Oscar-winning documentary “Born Into Brothels” delivers us into the sordid heart of Calcutta's red-light district, where bright, beautiful children grow up in conditions as poisoned and degrading as any on the planet.

So there's your ineffably sad part. The inspiring side of it comes from the kids themselves, in whose stories and attitudes we find not only a radiant portrait of youthful resilience, but also a meaningful lesson about the empowering virtues of art.

It all started in 1997, when Briski, a New York-based photojournalist, took up residence in the Calcutta brothels for an extended photo-essay. Connecting powerfully with the prostitutes’ children, Briski gave a group of them point-and-shoot cameras and sent them into the streets to photograph that rugged Indian metropolis on their own terms. As the movie's ad hoc narrator, Briski regularly appears on camera, tutoring the kids and championing their schooling. With her keen eye and halting Bengali, she cuts a peculiar but recognizable figure — part Mother Theresa, part Jane Goodall.

That might strike some as a patronizing analogy, but it holds up. The brothels, like the jungle, are a forbidding, impenetrable place, and the children — with no social apparatus to protect them — aren't treated much better than animals. Despite the hardships, the kids maintain a surprisingly philosophical outlook. “One has to accept life being sad and painful,” one little girl intones, evincing a wisdom, and cynicism, well beyond her years.

Like parched houseplants finally afforded water, the children brighten visibly when their photographic endeavors draw an international audience. Meanwhile, Briski hoofs it around Calcutta, trying to line up boarding schools for the kids and running aground on a shockingly dilapidated Third World bureaucracy.

By placing herself — and her charitable efforts — in the middle of the action, Briski risks developing a cinematic messiah complex, but it never happens. Though she labors aggressively on behalf of the children, she never pretends that their suffering is hers. The most pain she ever betrays is when her star pupil, a moody, instinctive photographic prodigy named Avijit, momentarily loses interest, and she shoots him a look of irritation. Thus, “Born Into Brothels” manages to arouse sentiment without resorting to sentimentality, and shows us activism at its best.