PARK CITY, UTAH -- Ashton Kutcher found playing Steve Jobs to be a "terrifying" experience.

Fortunately for him, Kutcher had the Sundance Film Festival to cushion his landing as he jumped into the lead role in "Jobs," a biopic that chronicles the life of the founder of Apple Computer (AAPL) from 1974 to 2002. In fact, he couldn't have found a friendlier place for the film to premiere.

This undated publicity photo released by the Sundance Institute shows Ashton Kutcher as Steve Jobs in the film, "jOBS," directed by Joshua
This undated publicity photo released by the Sundance Institute shows Ashton Kutcher as Steve Jobs in the film, "jOBS," directed by Joshua Michael Stern. (AP Photo/Sundance Institute, Glen Wilson)

The TV sitcom star got applause when he walked into the theater. He got applause when his name appeared in the opening credits. He got the typical, fawning plaudits in a Q&A session with the audience after the film's screening, which closed the Sundance festival Friday. It's not hard to feel loved when questions from the audience are peppered with comments about the "fantastic" movie and the "amazing" cast.

But Kutcher, nonetheless, seemed a bit nervous. He swayed back and forth onstage during the Q&A and barely cracked a smile.

"This was honestly one of the most terrifying things I've ever tried to do in my life, because I admire this man so much. And I admire the way he built things," he said of the film, which will open in theaters April 19.

"I admire the fact that you're filming this with an iPad right now," he said to one audience member.

Indeed, there was no small degree of irony in the fact that the theater was filled with people on their iPads and iPhones. "This guy created the tool that we use every day in our lives," Kutcher said. "And he believed in it when no one else did."

Starting off with a scene in which Jobs unveils the iPod to appreciative Apple employees in 2001, the film then backtracks to the beginning of Jobs' career. The film omits the last decade of Jobs' life, when some of the most important Apple inventions came into being and when Jobs' legacy was cemented with the emergence of Pixar, which was acquired by Disney in 2006.

Although the film has its moments of idol worship -- the soaring, heroic music that plays when Jobs introduces the iPod is more than a bit over the top -- "Jobs" doesn't shy away from his incomprehensibly bad behavior toward his oldest child or his abuse of colleagues.

Kutcher, the star of CBS' "Two and a Half Men," admitted that it was tough to play an icon who remains "fresh in our minds."

Actor Ashton Kutcher, who portrays Apple’s Steve Jobs in the film "jOBS," poses at its premiere during the 2013 Sundance Film Festival on
Actor Ashton Kutcher, who portrays Apple's Steve Jobs in the film "jOBS," poses at its premiere during the 2013 Sundance Film Festival on Friday, Jan. 25, 2013 in Park City, Utah. (Photo by Danny Moloshok/Invision/AP)

"I've never seen Abraham Lincoln walk into a room," Kutcher said. "I've seen Steve Jobs walk into a room." Playing Jobs was a bit "like throwing myself into this gauntlet of massive amounts of criticism."

Indeed, Steve Wozniak, Jobs' partner in the early days of Apple, has already said that the one scene of "Jobs" he has seen was "totally wrong." Wozniak is a consultant to another Jobs film being written by Aaron Sorkin ("The Social Network") from Walter Isaacson's best-selling book.

Director and co-writer Joshua Michael Stern ("Swing Vote") acknowledged that "these are really hard movies to enter because there's a lot of expectations." He said his goal was to give filmgoers "a feeling of what happened" and "finding the essence of who these people were." (There is a disclaimer at the very end of the credits saying portions of the film might not be completely accurate.)

When it came to casting Kutcher as Jobs, Stern said he "instantly knew that he was very invested in this role. I felt instantly that it was important to him on many levels."

Kutcher said he worked hard to get Jobs right. Not only did he watch 100 hours of film footage and listen to speeches he delivered, but hehe also lost "a tremendous amount of weight" to look more like the real Jobs.

He even tried Jobs' fruitarian diet -- which included just fruits, nuts and seeds -- but that didn't work out well. It "can lead to severe issues," Kutcher said. "I ended up in the hospital, like, two days before we started shooting the movie. I was doubled over in pain.

"And my pancreas levels were completely out of whack. Which was really terrifying, considering everything." (Jobs died of pancreatic cancer in October 2011.)

And, Kutcher added, "what was nice was when I was preparing for the character, I could still work on product development for technology companies, and I would sort of stay in character, in the mode of the character. I didn't feel like I was compromising the work on the film by working on technology stuff because it was pretty much in the same field."

Kutcher works closely with tech firms as a consultant and investor. Kutcher's A-Grade Fund -- cofounded with Los Angeles billionaire Ron Burkle and Madonna's manager, Guy Oseary -- has invested in an A-list of hot startups. Among them are Flipboard, Airbnb and video chat site Airtime, a collaboration between Napster co-founders Shaun Fanning and Sean Parker.

"Steve Jobs is a hero to me," Kutcher said. "He's a guy who failed and got back up on the horse. And I think we can all relate to that someplace in our life."

Bay Area News Group wire services contributed to this report.