“We got our baby back,” Gary Streiner, one of the film’s producers, said in a phone interview.

The process, Mr. Streiner said, began in earnest last year, when he; his brother, Russ (who co-produced and also played Johnny in the movie); and the screenwriter John Russo resolved to make a proper inventory of the film’s surviving elements, going through their own archives and the archive of the lab that originally worked on the film.

They turned to MoMA for help, partly because of its history with the film and partly for a practical reason. “Our vaults are in Pennsylvania,” said Katie Trainor, the MoMA’s film collections manager. “Once they had the materials together, they did not want to risk shipping them; they drove them from Pittsburgh. They were literally looking over my shoulder as I was inspecting the materials.”

Mr. Streiner recalled his relief at finding the negative in decent shape: “We could have opened the cans and found dust!”

The restoration was backed by, among others, the Film Foundation, the preservation nonprofit started by the director Martin Scorsese. In an interview, its executive director, Margaret Bodde, said, “The movie had been on a wish list of ours for some time,” and it helped “that we had the director around to consult with, which is too rare in film restoration.”

Mr. Romero said that it had been years since he had seen the film presented in its proper aspect ratio, a squarelike 1.37 to 1; many versions had been cropped to wide-screen proportions. “The restoration is very beautiful, and of course the movie’s pimples do show,” he said. “There’s a copy of the script visible in one of the frames! I won’t tell where. It will be a little challenge for fans to spot it.”