There was a time when 3-D movies were just a money-making gimmick. The technology, as primitive as it was, created an amusement-park like experience by having a variety of objects — yo-yos, knives and even sharks — jump off the screen and right into your lap.

“Up,” “Monsters vs. Aliens,” “The Jonas Brothers 3-D Concert Experience” and, opening today, “G-Force,” are among the increasing number of movies in 3-D.

“Coraline” (Universal, available now) is another, and it is a wonderful example of how 3-D has grown up to become a technology that enhances a movie. Sure, there are times when objects pop off the screen, but the technology is used mainly to give the film a beautifully realized, pristine depth.

Though it is based on a “children’s” book by Neil Gaiman, “Coraline” is certainly not a movie for all kids — it’s too scary. In fact, “Coraline” would have made a great episode of “The Twilight Zone,” or a deliciously creepy live-action movie in the hands of an imaginative director like Guillermo del Toro. Little girl lost goes through a magical door in the wall to an alternate universe where she meets her “other” mother and father — seemingly perfect parents with buttons for eyes.

As with most alternate universes, things aren’t as they first appear and little Coraline (voiced by Dakota Fanning) will have to face many frightening moments to get back to her real life.

The movie is released as a one-disc DVD ($29.98), a two-disc collector’s edition ($34.98) and Blu-ray ($39.98). Each has a 2-D and 3-D version of the movie plus four pairs of paper glasses and a commentary with director Henry Selick (the director of “The Nightmare Before Christmas”) and composer Bruno Coulais.

“Coraline” was shot using stop-motion animation, a painstaking process in which a figure or puppet is moved once for each frame in a movie (there are 24 frames in a second). The animators put that in perspective in the making-of feature on the collector’s edition and Blu-ray.

On a really good week, we’re told, 7 seconds of film is created by each artist. Animator Suzanne Twining describes a scene she is creating that is 24 seconds long. “It will take 3z weeks to shoot.”

The collector’s edition also has deleted scenes and the feature “Voicing the Characters.” The Blu-ray comes with the feature “Creepy Coraline,” a BD-live feature and U-Control. Those multidisc sets also have a digital copy.

Watching the movie at home with paper 3-D glasses was a disappointing experience. The images and colors were not as sharp as watching the 2-D version. In fact, the movie’s already muted colors often washed out to look nearly black and white while watching it in 3-D. (The pink house was closer to a light brown.) Plus, those paper glasses quickly brought on a “3-D headache.”

It was 163 minutes in the theaters, but that wasn’t enough to capture the essence of Alan Moore’s “unfilmmable” graphic novel. “The Watchmen Director’s Cut” arrived on DVD and Blu-ray this week with an additional 25 minutes of footage from filmmaker Zack Snyder including the murder of Hollis Mason that closely mirrors the graphic novel, plus more of Rorschach (Jackie Earle Haley).

The movie is available as a single-disc without bonus features ($28.98). The two-disc DVD ($34.99) and Bluray $35.99) have a digital copy and bonus features including “The Phenomenon: The Comic That Changed the World,” a music video by My Chemical Romance and Webisodes.

The Blu-ray also has the “Warner Bros. Maximum Movie Mode,” with side by side comparisons of the graphic novel and film; time-line comparisons of the “real world;” and “Watchmen” world.

Coming Tuesday

“Bad Lieutenant: Special Edition” (Lionsgate), “Bart Got a Room” (Anchor Bay), “Comic Legends” (MPI Video), “Fast & Furious” (Universal), “Liberace: Greatest Songs” (MPI).

TV on DVD: “Agatha Christie: Poirot&Marple” (A&E), “Dollhouse: Season One” (Fox), “A Touch of Frost: Season 14” (MPI).