‘Not to sound idiotic or pretentious, but I never start these things to be controversial,” Baz Luhrmann said recently in his Australian drawl.

He was pacing around an upstairs room in the Ace Hotel in Manhattan while tugging at the bottom of a several-sizes-too-small navy blazer he was wearing along with a rep tie, a pressed white shirt, carefully untucked, and shiny brown oxfords without socks. “I never start thinking they’re going to be a big deal.”

He was talking about his movie version of “The Great Gatsby,” the first draft of which was written in that very room because the view out the windows felt like 1920s New York, Luhrmann explained.

The film, which stars Leonardo DiCaprio, Carey Mulligan and Tobey Maguire and opens Friday, was shot in 3-D and includes such non-Fitzgeraldian elements as a soundtrack produced in collaboration with Jay-Z and songs by Beyonce, Fergie and Jack White; a lengthy near-orgy near the beginning and party scenes that might have taken place at the old Studio 54; and a framing story that has the novel’s narrator, Nick Carraway, writing “The Great Gatsby” while being treated for “morbid alcoholism” at a sanitarium modeled after the Menninger Clinic.

Luhrmann, 50, insisted that he originally conceived of “Gatsby” as drawing-room drama, and that the person responsible for making the film “epic” was really F. Scott Fitzgerald. “That ... genius goes and compresses the book, and then you’ve got to go blooey,” he said.

Sitting on a sofa while Luhrmann stalked back and forth was his wife, Catherine Martin, 48, — or C.M. as he and everyone else calls her — the production and costume designer on “Gatsby,” as she has been on all his films. She looked at him admiringly while waiting, as she often does, to get a word in edgewise, and said at one point: “You’re looking at the Australian Gatsby. He has to have a romantic vision that’s enormous.”

By now it’s practically conventional wisdom that Fitzgerald’s novel is unfilmable because its real power comes not from the plot but the prose. Before Luhrmann’s, there have been five attempts (if you count the dreary, low-budget 2000 made-for-TV version starring Toby Stephens and Mira Sorvino), none of them very successful. In 1926, the year after the novel came out, there was a silent-movie version directed by Herbert Brenon and based on a Broadway play by Owen Davis, a well-known script doctor of the period. All that survives of it now is the trailer, which shows some promising party scenes, including one of scantily clad women diving into a swimming pool to fetch gold coins, but also a Gatsby — Warren Baxter — who is pretty charmless.

The Davis play, which Fitzgerald himself didn’t much care for, was also the basis for the 1949 “Gatsby,” starring Alan Ladd. It’s essentially a gangster flick, with Gatsby depicted as a surly social-climbing bootlegger who repents at the end while, for some unfathomable reason, the earnest Nick Carraway and the dishonest Jordan Baker go off together and apparently get married.

Luhrmann was in junior high and living in a remote town in New South Wales, where his father ran the local cinema, when the 1974 “Gatsby,” directed by Jack Clayton (from a screenplay by Francis Ford Coppola) and starring Robert Redford and Mia Farrow, came out. This is the version that Vincent Canby, writing in The New York Times, famously called “lifeless as a body that’s been too long at the bottom of a swimming pool.” At the time, Luhrmann was a big Redford fan, but he recalled being baffled by his Gatsby. “I just didn’t understand who this guy was,” he said.

One of the difficulties with “Gatsby,” Luhrmann went on, is that the title character is a sort of cipher. There’s not much actual description of him in the book, other than that he’s “an elegant young roughneck” and that his “elaborate formality of speech just missed being absurd” — so readers tend to project their own versions.

“Everyone has their own Gatsby, their own Daisy,” Luhrmann said. He added that the character is more mercurial than many readers think — or than you would ever know from the Ladd and Redford performances — and that this was something DiCaprio had caught singularly well.

“When you first see him, he’s the coolest guy in the world,” he said. “The next moment he’s Buster Keaton, and then he’s the Prince of Wales. He’s nervous and psychotic, and then he’s dark and intense. He changes the character constantly because Gatsby picks stuff up. He’s performing the character of Jay Gatsby.”

Luhrmann is a great admirer of “Gatz,” the Elevator Repair Service’s stage re-enactment of the novel and so far the most successful adaptation, in part because it’s so literal: every single word of the text is spoken aloud, including the he saids and the she saids. “But that production takes seven hours,” Luhrmann said, “and that wasn’t an option for us. We weren’t making a miniseries.”

The hard part of making a movie of “Gatsby,” he went on, was determining what from the text could be left out, while also figuring out a way to externalize the sensibility of Nick Carraway (Maguire), in whose head the whole story takes place. That’s where the sanitarium comes in, he explained. He wanted not just to use a voice-over but to dramatize that Nick is in the midst of writing the novel, coming to terms with Gatsby and with himself as he goes along.

“And we know that the Fitzgeralds were not strangers to sanitariums,” Martin pointed out.

Luhrmann and his wife are obsessive researchers, the sort of people, she explained, who would almost rather do the homework than make the movie. By now they both can quote by heart great chunks not only of “Gatsby” but of “Trimalchio,” Fitzgerald’s earlier draft, and Luhrmann’s website offers a reading list that amounts to a grad school seminar on Fitzgerald. Between them they have a textual or historical justification for just about everything in the movie.

Inflatable zebras in the swimming pool? Absolutely. Martin has period photographs. The scholars who insist that it was a Rolls that ran over Myrtle Wilson and not, as in the movie, a Dusenberg? They don’t know their cars, and they haven’t looked carefully enough at the text. The metallic Prada gown that Daisy wears to one of Gatsby’s parties? That style was just coming in. People have a mistaken notion of ’20s fashion. It’s not just flapper dresses. And there is hip-hop music in the film, Luhrmann said, because hip-hop now is what jazz was then.

The collaboration with Jay-Z came about because of a chance meeting, he explained, but all along he had thought that “whatever jazz is now, it’s revered; it’s an older music,” and he wanted audiences to feel the excitement that readers would have felt in the ’20s.

“Jazz in 1922,” when the novel is set, “was being referred to as an African-American fad,” he said. “Why would Fitzgerald put such ephemeral stuff, actual song lyrics, in his book? Because it made it immediate and visceral and exciting for the reader. And when you think of an African-American street music today that is visceral and exciting and is making a big impression on popular culture, that’s hip-hop.”

Luhrmann is well-aware that for many people “The Great Gatsby” is practically a sacred text. “ I can hear the chorus: ‘Oh, my God, what’s he done to it now!’ ”

He added that he wasn’t bothered by the book’s reputation for unfilmability. “I’d have been more worried if there had been a successful one,” he said, referring to past film versions, “or if I was trying to remake ‘Citizen Kane.’ I guess I try to medicate my terrors by throwing myself into impossible tasks.”