LOS ANGELES: Johnny Depp has abandoned flashy pirate gear, wigs and other “clown nose” costumes to plunge into the serious, even cerebral “Transcendence,” a sci-fi thriller about nanotechnology.

Known for his “Pirates of the Caribbean” dreadlocks, “Alice in Wonderland”top hat and “Lone Ranger” face paint, Depp slips into the less colorful role of a scientist whose brain is uploaded into a huge computer just before his death.

Combining human intelligence, digital super-power and a form of immortality, he rapidly succumbs to the somewhat cliched temptation to dominate the world, leaving his wife (played by British actress Rebecca Hall) in desperate straits.

Despite the often weighty tone of the movie -- which opened in the United States on Friday amid some poor reviews -- the 50-year-old actor managed to find some humor when talking about it.

“Well, having no intelligence, I'm looking forward to gaining something, whether artificial or superficial,” he quipped at a Beverly Hills press conference with his fellow actors and filmmakers. - 'Can't stand the way I look' -

Becoming serious again, he conceded: “For me, it's always more difficult and slightly exposing to play something close to yourself.

“First, I always try to hide because I can't stand the way I look. I think it's important to change every time and do something that's as interesting as you can for your characters.”

But an actor's choices are not the only ones in how a role is played.

“You have the author's intent, the filmmaker's vision and then you have your own wants, desires and needs for the character. It's collaborative,” he told reporters.

In “Transcendence,” Depp said he “knew right off the bat certainly there was no need to go into some pink-haired, clown nose, Ronald McDonald shoes.

”The movie is a first directing credit for Wally Pfister, who was director of photography on a number of blockbuster filmmaker Christopher Nolan's films, including on the three “Dark Knight” movies and “Inception,” which won him an Oscar in 2011.

Pfister told AFP he was seriously worried about whether he was up to the challenge.

“The most scary thing was choosing the right material. If you're going to pick such a risky move in your life, you surely want to be careful about the material that you're going to choose and the story that you're going to tell,”he said.

The heart of the film, he said, is the conflict between man and machine.

Pfister also highlighted the environmental dimension, embodied in Hall's character, who wants technology to help save the planet.

“Her belief is that technology should be used for the betterment of mankind,” he said.

“It's very important to her, and one of these aspects is, if we're going to create this nanotechnology, if we are going to have the world's most powerful machines, why don't we use it to fix some of the mistakes that we have made?

“And one of those mistakes, in her mind, is what the industrial complex has done to the world.”

Depp admitted that he was a long way from the master of technology he plays in the movie.

“Things go wrong all the time, especially between me and technology. I'm not familiar with it, and I'm too old-school a brain and dumb to be able to figure it out,” he said.

Pretending to tap out a text on his cell phone, he added: “Anything I have to attack with my thumbs for any period of time makes me feel stupid.

So I try to avoid it as much as possible -- to protect my thumbs, of course.”Critics have not been kind to Pfister's directing debut: it has only an 18 percent positive rating on the Rotten Tomatoes movie review website.

“Ace cinematographer (Pfister) remains a distinctive visual stylist, but Transcendence's thought-provoking themes exceed the movie's narrative grasp,”it said.