Oscar-winning director Danny Boyle on Thursday defended the gory scenes in "127 Hours", his new film about a mountaineer forced to amputate his arm, saying the movie was about being reborn.
Starring James Franco, "127 Hours" tells the true story of US climber Aron Ralston, whose right hand became trapped under a boulder when he slipped into a canyon in a remote area of Utah.
For five days - or precisely 127 hours - Ralston tried desperately to free his arm, knowing he had not brought a mobile phone on the trip and had failed to tell anyone where he was.
Reduced to drinking his own urine and weakened by hunger, Ralston recorded a series of video messages to be viewed by his parents after his death before coming to the terrible conclusion that his only hope of survival was to cut off his lower arm.
He had no penknife, so was reduced to hacking away at the limb with the contents of a small portable toolkit.
The amputation, shown in excruciating detail in the film, caused several people to faint in test screenings.
But speaking ahead of the European premiere in London, "Slumdog Millionaire" director Boyle said anyone would have done the same in the same situation.
"We'd all do it. We'd chew it if we didn't have a knife," he said.
While the film appears bleak, Boyle argued the central message was one of hope.
"It's very disturbing but it's worth so much more. Life is given back to him. It's about childbirth."
Screenwriter Simon Beaufoy said the filmmakers "had a responsibility to Aron to stick to what he actually lived".
"Aron accepted his own death and he didn't know there was going to be a happy ending," said Franco, whose performance as Ralston has led some critics to tip him for an Oscar.
Franco, who previously starred in the "Spiderman" trilogy, said he enjoyed working with Boyle because he "really looks to challenge himself to different material, to pull him out of his comfort zone.
"It enables him to make a different movie every time."
"127 Hours" opens in the United States on November 5 and in Britain on January 7.