NEW YORK, N.Y. – The colorful palette of Spike Jonze’s wistful, slightly futuristic digital romance “Her” had an unlikely inspiration: Jamba Juice.

Jonze premiered his highly anticipated film Saturday at the New York Film Festival, where he and his cast, including star Joaquin Phoenix, exemplified none of the interpersonal disconnect of the movie’s sleek but melancholy future. They entertainingly debuted the film for critics and film industry members ahead of an evening red-carpet premiere that was to draw the 51st New York Film Festival to a close.

Phoenix stars in the film as a recent divorce who purchases and gradually falls in love with an artificial operating system named Samantha (voiced by Scarlett Johansson). The system, dubbed OS1, is something like a far more advanced version of the iPhone’s Siri, advertised as an “intuitive entity” and “a consciousness.”

Jonze said in a post-screening news conference that he wanted to set “Her” in a somewhat utopic Los Angeles that “felt nice to be in.” It shares some of the colour of the smoothie franchise Jamba Juice and is forested by skyscrapers. Jonze, who wrote and directed the film, borrowed the skyline from Shanghai, where much of the movie was shot.

It was an interesting acting challenge for Phoenix, given that his primary co-star was a disembodied voice. The character was initially voiced by Samantha Morton before Johansson took over the role.

“I’d like to say that I trained, but as an actor, I’m accustomed to walking around my house and talking to myself,” Phoenix said. “We rehearse all the time so I don’t think it was that dissimilar.”

Phoenix is known for his distaste for public appearances and media interaction, but he was in good spirits Saturday, playfully answering questions or cheerfully ignoring them. On capturing the loneliness of his character, Phoenix replied that “Spike just broke me.”

“Going into the movie, all I was concerned about was trying to feel natural in something that wasn’t there,” he said. As to how he managed to “break” Phoenix, Jonze fumbled for an answer before guessing, “I think he’s joking?” while Phoenix nodded.

The actor even ironically admonished co-star Rooney Mara, who plays his ex-wife, for not eagerly answering questions.

“Rooney, don’t do that,” Phoenix said. “I’m so sorry everyone.”

Warner Bros. will release “Her” on Dec. 18.

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Follow AP Film Writer Jake Coyle on Twitter at: http://twitter.com/jake_coyle