“Harold and the Purple Crayon,” the famed 1955 children’s picture book, is getting the three-dimensional treatment nearly 70 years after its release.

The picture book, written and illustrated by Crockett Johnson, follows Harold, a child who can create whatever he can imagine, so long as he draws it with his magic purple crayon. The film adaptation opens with a short animated sequence that gives life to the book’s famous illustrations. But how far can a children’s picture book stretch across an hour and a half-long movie? Not very.

After the film gets through the book’s story in about a minute, the narrator says that the book’s ending was not the close of Harold’s story. Cut to an animated adult Harold, all grown up but still in a onesie, with his purple sketched friends, Moose and Porcupine, as they venture around their two-dimensional existence and wonder what goes on in “the real world.”

After some brief exposition and short narration by Alfred Molina, Harold (Zachary Levi) draws a door labeled “Real World” and walks through it. He’s then miraculously spit out in Providence, Rhode Island, as a “real” person. Moose and Porcupine, played by Lil Rel Howery and Tanya Reynolds, respectively, follow through the magical door shortly after. Together, they embark on a mission to find the book’s narrator and author — the “old man,” as they call him — to ask him why he created them and their story.

What we get from there is something that feels like a hybrid of characters played by Amy Adams in “Enchanted” and Will Ferrell in “Elf”: an adult person who left their animated or fantasy world and is incredibly unfamiliar with reality. It’s an entertaining idea to see someone so naive navigating everyday life, but it feels rather derivative.

Much like her character in “Elf,” Zooey Deschanel plays Terry, a “real world” woman who is unenthused by our other-worldly protagonist’s antics for the better part of the movie. As the mother of the young and creative Mel (Benjamin Bottani), Terry hits Harold and Moose with her car, and eventually lets them stay at her house after some convincing from her son.

Predictably, shenanigans ensue as Harold lacks understanding of how to behave as the adult everyone sees him as (and wreaks havoc with his magic crayon). Levi is terribly earnest as Harold, making his hijinks more endearing.

Director Carlos Saldanha, an animation veteran who helmed the “Ice Age” franchise and the “Rio” movies, keeps the story moving with light humor and fun visuals sprinkled throughout. The imaginative animation over the live-action shots is the movie’s highlight, as Harold can still create anything with his purple crayon in the real world. With more colors and dimensions to play with now, he draws everything from a plane they fly over Rhode Island to Mel’s imaginary pet, which is some sort of dragon-lizard hybrid.

The plot, again, feels familiar when we meet the villain, librarian Gary, who wants to wield the powers of the crayon to feed his self-serving interests. Gary (Jemaine Clement) uses the crayon to make the fantasy world of his failing book come to life so he can get “revenge” on the publishers who turned it down. As far as conflict goes, it falls a little flat, but it does result in a sweet lesson of empathy; Gary says he just wanted to be in a place where he can fit in and Harold, using the crayon for good, creates that world for him.

While much of the movie may feel well-worn, I’d wager many copies of “Harold and the Purple Crayon” have seen better days. It’s the kind of children’s book that’s stayed on shelves through multiple generations. Even if the book’s story has been told and the movie’s format has been done before, a movie that reminds us to be imaginative — and that delivers some imaginative visuals to boot — can’t really get old.

“HAROLD AND THE PURPLE CRAYON”

Rated PG. At the AMC Boston Common, South Bay Center, Causeway and suburban theaters.

Grade: B