"This movie probably has a bigger on-screen body count than any movie I've done before," Singer said. "It's done in a way that's fun, but it was a challenge to get away with that without it becoming upsetting to people."

To achieve something appropriate for kids 7 to 11 years old while not alienating teenagers, Singer toned down the sound effects, specifically a crunching sound, when the giants devour the humans. He also scrapped his original intro — one he recorded three different times with narrators including Julie Andrews and Ian McKellen.

Singer returned to the set, this time in New Zealand, to create a more family-friendly introduction that explained the mythology of the giants in a bedtime-story format read to two children who would grow up to become the film's protagonist, Jack, and its princess.

"It was about creating a tone like 'Raiders of the Lost Ark' or 'Star Wars' that allows you to get away with a lot of stuff because it feels like a movie," Singer said. "It's clearly a movie. It's not 'Zero Dark Thirty.'"

PHOTOS: Hollywood Backlot moments

Pre-release tracking surveys suggest "Jack" won't open to more than $25 million this weekend, with the young male audience most likely to show up. The filmmakers hope that the family audience is not being polled accurately and will attend in greater numbers than surveys suggest.

"You are always hoping for a surprise from the family audience," said Dobkin, who remained a producer on the film. "A family makes a decision what they are going to do right before the weekend. Based on the testing, kids love the movie."

Had the film opened last summer, it might have performed better, but Singer is content with the delay.

"It's funny — in the time this movie took from start to finish, I've already written, produced, executed and released one 'X-Men' film and developed another one that's currently in pre-production," he said, referring to "X-Men: First Class," which he produced, and the upcoming "X-Men: Days of Future Past," which he will begin shooting next month.

"I'm happy it took this long. I could fix things on 'Jack' that wouldn't have been qualitatively as good if I didn't have the time."

nicole.sperling@latimes.com