Actress Kristen Stewart poses at the gala presentation for the film "On the Road" at the 37th Toronto International Film Festival September 6, 2012.[Photo/Agencies]

The Toronto film festival opened on Thursday with action movie "Looper" starring Joseph Gordon-Levitt, but it was "Twilight" star Kristen Stewart who attracted the biggest buzz on the red carpet at the star-studded festival scattered with Oscar hopefuls.

Anticipation was high for one of the world's premier film festivals that coming off Venice helps mark the beginning of Hollywood's awards season. Filmmakers see it as crucial launching pad and Toronto has previously propelled such films as "The King's Speech" to go on to success at the Academy Awards.

Ben Affleck, Selena Gomez, Halle Berry, Tom Hanks and rapper-turned reggae wannabe Snoop Dogg, now known as Snoop Lion, are all among a lineup of top stars due to appear.

But it was Kristen Stewart who wowed the red carpet Thursday, signing autographs to streams of cheering fans in her first media appearance since issuing an unusual public apology for cheating on long-term boyfriend and "Twilight" co-star Robert Pattinson with British film director Rupert Sanders.

Without directly referring to the scandal, Stewart, 22, told Reuters she was thankful "to know that everyone is here" and the support she described as "amazing" before she walked into the premiere of "On The Road" based on Jack Kerouac's seminal book of the postwar Beat Generation.

At a nearby theater, "Looper", a futuristic action blockbuster featuring Gordon Levitt and Bruce Willis about an assassin haunted by his time-traveling future self, officially kicked off the 11-day festival that will screen more than 280 films.

"CLOUD ATLAS" AHEAD

Johnson and the film's stars said they believed the film had more emotional appeal than pure blockbuster entertainment value.

Asked about the violence in "Looper" and the wider movie world coming off the Colorado movie house massacre where during a screening of "The Dark Knight Rises" in July a gunman killed 12 people, Willis defended violence in the movies as a part of their integral, emotional pull.

"Violence is one of the hard, bad things that exist in the world. It's not just in films; it exists anywhere," he told reporters. "And to pick one thing out and say 'Well, you shouldn't have violence in films or you shouldn't make violence a part of a film, would be like taking the emotion out of it."

The movie's themes also prompted questions for the two stars about time travel and what they might change in the past. Gordon-Levitt said he would like to see the future - "I consider myself an optimist" - while Willis reflected: "I would remind myself every couple of minutes not to take myself seriously."

By Friday, the festival will quickly turn toward some of the more anticipated films already gaining Oscar buzz, including Ben Affleck's "Argo," based on the story of how the CIA smuggled six Americans under the cover of a Hollywood production during the 1979 Iran hostage crisis.

Also competing for critics and audience attention will be Paul Thomas Anderson's "The Master," David O. Russell's "Silver Linings Playbook" and "Cloud Atlas", an adaptation of the best-selling novel directed by Tom Tykwer and "Matrix" co-directors Andy and Lana Wachowski and starring Tom Hanks and Halle Berry.

Optimism by sellers and buyers added to the festival's excitement, with its reputation as a hot marketplace for its ability to grab media attention and attract quality productions.

Summing up why Toronto has quickly risen from its launch in 1976 to become one of the world's most desirable film destinations, Gordon-Levitt noted its reputation for low-key serious moviegoers.

"This is a festival that is full of cinephiles," he said. "It doesn't have the air of glitz and glamour and I really like that about it. It's more about the films."