Film-maker Jakob Schuh so reveres British writer Roald Dahl that he dared not change a word when adapting Dahl's Revolting Rhymes, a collection of poems reimagining classic children's fairy tales.

"Dahl's stories are incredibly funny and witty. You don't want to change any of that," says Schuh, 41, in a telephone interview with The Straits Times.

The 2016 two-part animated feature film will be screened here as part of the Big Eyes, Big Minds - Singapore International Children's Film Festival, which opens today at the National Gallery. The two parts, each 30 minutes long, will be screened in separate sessions from May 27 to June 11.

In the animated film, Dahl's dark interpretations of five classic fairy tales are woven into a single story and narrated by a central character, a wolf voiced by British actor Dominic West.

Schuh, who directed the film with Jan Lachauer, says: "At some point, it became a maths exam. We physically cut the story into little pieces and then just tried it all out on a large table."

He says another challenge they faced was adding elements to the plot, such as the friendship between Red Riding Hood and Snow White, without adding additional text, especially during the narration of the rhymes. The film ended up taking about 21/2 years to complete.

Schuh - who made his mark in children's film directing the 2011 Oscar-nominated short film The Gruffalo, an adaptation of the popular book by Julia Donaldson - also has the highest regard for illustrator Quentin Blake, whose art is found in many of Dahl's books.

So, he did not attempt to reproduce Blake's pictures in Revolting Rhymes.

"To me, it would feel like blasphemy to try and recreate the artwork of Quentin Blake," he says.

"Sir Quentin's artwork has a certain amount of inexplicable magic and you don't want to mess with that."

Unlike his adaptation of The Gruffalo, which closely followed the book's original illustrations by Axel Scheffler, Blake's "gorgeous twisted scribbliness" was more difficult to rework into a 3D form, says Schuh.

Outside of film adaptations, he has done mainly short films and commercials since graduating from Film Academy Baden-Wurttemberg in 2003, many of which are targeted at children.

Despite having worked with youngsters extensively for his films, Schuh, who has no children, says he never fails to marvel at how and what the young ones think.

At a recent screening of Revolting Rhymes in New York, a young girl went up to him wanting to know the names of two unnamed characters in the films.

"When I explained to her that we never named them during the production, she was slack-jawed, because in her mind, they had to have names," he says.

"The fact that they didn't have names was not an option. For these kids, the characters are real."