HOLLYWOOD — It’s telling that on the official Cannes Intl. Film Festival Web site, “Apocalypse Now” has always been noted with the parenthetical “A Work in Progress.” That is precisely what it was in 1979, when director Francis Ford Coppola accompanied his then-unfinished Vietnam epic to the Croisette, where it grabbed the Palme d’Or.

Over two decades later, it is “Apocalypse Now Redux,” and it is unfinished no longer.

In a virtually unprecedented effort to both restore, revise and expand an already well-established work of film lore and spectacle, Coppola, with the close collaboration of sound designer Walter Murch, cinematographer Vittorio Storaro and producer Kim Aubry, has added 54 minutes of scenes and sequences filmed and then cut from the original release.

Due for U.S. theatrical release, courtesy of distrib Miramax in August, the hallucinatory adaptation of Joseph Conrad’s “Heart of Darkness” will be presented in its initial premiere format, sans titles and credits, with a handout program for the audience. The running time: at three hours, 16 minutes.

But the pic’s debut, appropriately enough, will be at this year’s Cannes, a prime fest showcase and natural homecoming for the project, and a return to what has been one of Coppola’s most receptive venues. He was first at Cannes in 1967 with “You’re a Big Boy Now,” won the Grand Prix in 1974 for “The Conversation,” returned — after the 1979 triumph — in 1989 as one of three helmers repped in “New York Stories,” and most recently headed the jury in 1996.

Eventually, “Apocalypse Now Redux” will appear on homevideo and DVD, but when the expansion project began in 1999, the small-screen market was the only one in mind.

Paramount, owner of the film’s home entertainment rights, informed Coppola at that time of their plans for a DVD release.

“We wanted to be closely involved,” says Aubry, “because we had seen what had been done in various DVD releases up to that point, and didn’t like the results.”

Coppola’s Zoetrope company became the principal firm overseeing the DVD production, seeking the best sound and image elements, with added commentary tracks.

Yet, Murch recalls, “Francis and I had long talked about the possibility of going back and retrieving many scenes that we just didn’t quite have the nerve to include in the original release. Perhaps it was a conservative streak that emerged, but there was real concern in 1979 that audiences weren’t going to put up with the amount of material in the original script.”

At the annual harvest party at Coppola’s Napa winery in 1999, the key “Apocalypse” players were all together, and after the project was brought up again in conversation, it took flight. Aubry oversaw a monthlong review of where the film and sound elements were (the film was stored in limestone caves in the Poconos; the sound was in safe keeping at Coppola’s estate) and how much of the 2 million feet of material was to be used.

Reviewing the negative, Murch found 12 potentially usable new scenes and sections, but whittled it down to eight.

“The criteria,” says Aubry, “was the strength of the performances, and if the scenes had been fully shot and covered.”

The new additions include:

n A “French plantation” sequence featuring Aurore Clement and the late Christian Marquand as Gallic colonial holdovers whom Martin Sheen’s Willard and his crew encounter upriver.

n A Patton-like speech by Robert Duvall’s Col. Kilgore.

n Three love scenes.

n A scene in which Marlon Brando’s Kurtz peruses a Time magazine, poking fun at the U.S. press’ coverage of Vietnam.

“It was not only a matter of addition,” notes Murch, “but of restructuring, and sometimes placing certain scenes at different points. The additions also clarify some points, as when Clean, played by Laurence Fishburne, is killed. In the original, we never see him buried. Now, we do, at the French plantation.”

The “Redux” project also contained some notable technical matters. Murch found that the old DVX soundtrack, which was then state-of-the-art, was “actually too good for the digital transfer, the dynamic ranges are so remarkable. In adding the old track, we had to come up to the standards of the original mix, so it was the audio equivalent of fabric re-weaving.”

Once it was clear to Coppola that “Redux” deserved a full-on theatrical release, Storaro examined the prints of the negative and found that the image degradation was such that the results for release prints were completely unacceptable.

Storaro went to Napa and argued his case to Coppola that only a dye-transfer printing process, a specialty at Technicolor labs, would ensure color quality:

“It was essential that we were able to restore not only all the colors to full saturation, but that we achieved pure blacks and pure whites. True tones are degraded by 1% per year. Only dye-transfer prints remain intact and pristine through time.”

As for Coppola, who was unavailable for comment, Aubry reports that “he doesn’t feel attached to the old version. For him, this new version is ‘Apocalypse Now.’ ”