“Pencils vs. Pixels” is a brisk celebration of the hand-drawn 2D animator’s art and cursory history of its “golden ages,” the last of which ended as computer-generated imagery and digitally assisted 3D animation took over with the rise of Pixar and the birth of “Shrek.”

Filmmakers Bay Dariz and Phil Earnest got permission to use clips from a lot of Disney, Dreamworks, Don Bluth and Pixar films, including pencil test footage and digital experiments. They rounded up scores of the animators who worked on those films to talk about the nature of the work, the films that inspired them and the sad way CGI displaced the classical animation that they sketched, drew, inked and animated to life.

Their art was “black magic,” one animator notes, “a marvelous illusion — acting passion and physics on the page,” the great Glen Keane says. Some enthuse how “each frame was a masterpiece” back when artists designed and drew, inkers inked and painters painted images on cells that were filmed.

Working with pencil and paper, “artisans” who became “folk heroes” learned “what a 24th of a second feels like” as they mastered their craft, making cell animation “by feel” in the celluloid (24 frames per second) motion picture era.

We hear about the first Golden Age that the art form experienced, the Disney-driven “Snow White” to Jungle Book” epoch that produced timeless classics that were re-issued to theaters, again and again, so that new generations could discover the magic of animated movies on the big screen in that pre-cable, pre-home video and streaming era.

We learn about the Disney rebellion after “The Fox and the Hound,” which led to Don Bluth starting his own studio and releasing “The Secret of NIMH,” the Roy E. Disney-led Disney revival that burst forth with “The Little Mermaid,” which heralded a ’90s “Second Golden Age” and got Dreamworks and others into the animation business.

Being Disney-centric, there’s a lot here’s that’s been covered elsewhere in documentaries such as “Waking Sleeping Beauty.” But where “Pencils vs. Pixels” breaks new ground is in the transition that all but wiped out traditional hand-drawn animation. Animators like Keane and Andreas Deja and others sound as upbeat as they can about this revolution, and some even predict a return of hand-drawn animation in the digital age.

That could happen, as tastes in animated cinema trend towards “different. Thus, the 3D animated fad and its 3D glasses have all but disappeared. Stop motion animation has experienced an off-and-on renaissance with films such as “A Nightmare Before Christmas,” “Coraline,” “The Fantastic Mr. Fox” and “The Inventor” grabbing at least some of the audience’s attention. Hand drawn on a budget could come back via Netflix money.

“Pencils” lets us glimpse the first CG exeriments that led, years later, to Pixar and “Toy Story” and an entire industry being upended and remade, with every animation operation going CGI in a very short period of time.

As Disney-centric as this is, there’s still a warm appreciation for the work that Don Bluth and Steven Spielberg and John Pomeroy (seen here) made that woke the Mouse out of its torpor, “An American Tail,” which followed “NIMH.” “Competition” brought Disney Animation back to life.

Not being a major studio production, there are major figures in this story missing in this documentary, Spielberg among them. There’s no Jeffrey Katzenberg to talk up his “tradigital” transition strategy for Dreamworks, a way of maintaining the human creative touch in a computer-assisted, pristine and crispy animated look. Yes, that was mostly late ’90s PR spin from the “Shrek” studio, but it has a kernel of truth in it.

Although the two historians — Leonard Maltin being the most famous — and most of the animators paint a pretty complete picture, not everybody interviewed here has a lot to say on the subject that anyone needs to hear. Watch the movie and you’ll see who I mean. Limited screen time means every interview has to advance our knowledge and appreciation of the art form.

The film’s history is solid in some regards, shaky in others. Sampling the first attempts at computer animation, using it for the Inside Big Ben sequence in “The Rescuers,” a test for a Disney CGI-assisted “Where the Wild Things Are,” “Aladdin’s” magic carpet and the ballroom breakthough moment in “Beauty and the Beast” take us through the baby steps that changed the way animation is filmed.

Making the historical point about how master animators became mentors of the last Golden Age’s stars further burnishes Disney’s “Nine Old Men” myth, the senior animators who tied later generations back to the “Bambi/Fantasia” era talents. Many a famous animator of the ’80s and ’90s learned at the feet of one of these figures, immortalized in “Frank and Ollie.” But read any reputable Disney biography. “The Nine Old Men” entered Disney lore because Walt promoted and lionized them for crossing the picket line to keep production going during the famous 1941 strike that unionized the cartoon studio.

I spent years covering this “Pencils” and “Pixels” struggle while working for the newspaper in Orlando, where “Mulan” and “Lilo & Stitch” were largely made at the now long-closed Disney’s Features Animation Florida. Deja, a couple of the “Old Men” and others interviewed in this film, Roy E. Disney and Katzenberg, Pomeroy and Pete Docter and the rest all put the best face on this “business” decision as it was happening — CGI requires fewer human artists — back then and even now.

Being brisk and cursory, “Pencils” skips over the many abortive efforts by Disney and others that always kept hand-drawn animation on the ropes between hits. There’s a mention of “The Fox and the Hound,” no discussion of the failures that preceded it and followed it. Bluth and Pomeroy’s later successes (“All Dogs go to Heaven”) and blundering later efforts with various studios are left out.

Big screen animation was on life support pre-“Little Mermaid.” TV animation had drifted to the point where few felt tempted to call it “art.” Overnight, all that changed. “Pencils” does a decent job of laying out how that happened and crediting those involved.

And if nothing else, it’s refreshing to remember Walt himself and others revive the word “cartoons,” which makes arrested development “animated” fanboys of today turn purple with rage. Yes, they were and are great artists. And yes, most of them would say their art is animation “cartoons.”

Rating: unrated, G-worthy

Cast: Glen Keane, Andreas Deja, John Musker, John Pomeroy, Jorge Gutierrez, Leonard Matlin, Mindy Johnson, Pete Docter, Mark Henn, Bruce W. Smith, Aaron Blaise and many others — narrated by Ming-Na Wen.

Credits: Directed by Bay Dariz and Phil Earnest, scripted by Bay Dariz. A Strike Back Studios release.

Running time: 1:24