With his new documentary, “Amy,” Asif Kapadia wants to burnish Amy Winehouse’s legacy as one of the most influential vocalists and songwriters of the early aughts.

It’s a restoration project with challenges, and its subject’s slow disintegration in the public spotlight is largely to blame. By the time Winehouse succumbed to a mixture of bulimia, drugs and alcohol in 2011 at the age of 27, the “Back to Black” chanteuse risked being more famous for her off-, and even onstage, tumbles and brushes with notoriety than she was for her music.

Kapadia, who previously helmed the gripping racecar documentary “Senna,” admits that he was only dimly acquainted with Winehouse’s music when he took on the project. He knew more about her tabloid history than her talent.

Though “Amy” does not flinch from documenting Winehouse’s insatiable quest to achieve altered states, it makes a compelling case for her impact on a new generation of belters like Adele and Duffy, who echo her blend of R&B, jazz and swing.

“She made a big change in the business,” Kapadia said. “There are so many solo artists who are all quirky and unusual, and so many of them came after Amy and because of Amy.”

Critics love the film, praising the way it weaves in dozens of interviews amid archival footage of Winehouse performing and squandering her gift as she succumbs to crack and other addictions. An Oscar campaign appears inevitable. Heck, it could win the Golden Guy outright.

Audiences have embraced it as well. The film opened last weekend in the U.S. to a hefty $222,500 and a per screen average of $37,083, and it appears poised to be one of the summer’s big indie breakouts. In Winehouse’s native U.K., “Amy” scored the second biggest opening for a documentary in the country’s history.

“You spend years on a project and this is the real bit, when you hand it over to an audience,” Kapadia said. “It’s exciting to see how well it has gone down in London, where it’s more personal. It’s hitting home in a way, because a lot of fans never had a chance to grieve or cry or get emotional.”

Not everyone is thrilled with Kapadia’s work. The Winehouse family participated in the project, but Amy’s father Mitch comes off poorly in the picture. He is depicted as downplaying her addictions at critical moments and is seen bringing camera crews along for a reality series he was involved with at a particularly low point in his daughter’s life.

Mitch Winehouse has said he was “misrepresented” and made to appear as though he never supported his daughter’s efforts to get sober. He’s vowed to make a new film that will set the record straight.

Kapadia argues that he was trying to provide layered portrayal of Winehouse’s life and times, aiming to show the good and the bad, the highs and the lows.

“[Mitch] loved his daughter and she loved him,” he said. “I would never attempt to pick on someone or attack them. This was intended to show that at some points a lot of people were making decisions that were not what was best for Amy. I wanted this to be honest to Amy. Not to harm people.”

Winehouse may have had a coterie of enablers, but “Amy” is savvy enough to show the role that the media business played in exploiting her descent. Her antics became fodder for latenight comics and gossip rags when they should have inspired sympathy and concern instead of derision.

“We were complicit,” said Kapadia. “We shared videos, we clicked on stories, we paid to see someone just in case she was about to die. The movie ultimately becomes more about the media journalism machine and the audience for this stuff.”