It’s not a bug, it’s a feature.”

That’s an oft-heard refrain in the computer world, where programmers routinely trot out “improvements” that users experience as irritations and glitches.

The phrase came to mind a few weeks ago during CinemaCon, a confab of movie exhibitors in Las Vegas where Warner Bros. showed them 10 minutes of Peter Jackson’s hotly anticipated adaptation of “The Hobbit: An Unexpected Journey.” As reports filtered out of Caesars Palace, no one was talking about Elijah Wood’s Frodo or Martin Freeman’s Bilbo or how the action and meaning of J.R.R. Tolkien’s epic fantasy had translated to the screen. Rather, the blogs were agog with news about a new 3-D digital format Jackson used to photograph “The Hobbit,” at a souped-up 48 frames per second — twice as fast as the usual 24 frames per second of conventional film.

One exhibitor present reportedly compared the look to a behind-the-scenes featurette; Variety reporter Josh L. Dickey wrote that the new format lacked the “cinematic glow of industry-standard 24 fps.” Although computer-generated characters were a “distinct presence,” he continued, “human actors seemed overlit and amplified in a way that many compared to modern sports broadcasts . . . and daytime television.”

But at least one film-lover in Vegas liked what he saw. The “Hobbit” footage, wrote online film columnist Jeffrey Wells on his Web site, Hollywood Elsewhere, was “like watching super high-def video, or without that filtered, painterly, brushstroke-y, looking-through-a-window feeling that feature films have delivered since forever.” The high frame rate, he continued, “removed the artistic scrim or membrane that separates the audience from the performers.”

In rhapsodizing about the heightened realism and sharpness of the “Hobbit” footage, Wells pointed out an aesthetic trend that, to many viewers raised on the grain and texture of film, looks like a bug is well on its way to becoming a feature.

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Video initially presented a threat to film studios, before they learned to leverage it, both in production and as an added revenue stream. In time, it seemed as though video might even save the cinematic medium itself, financially and creatively. In the documentary “Hearts of Darkness,” Francis Ford Coppola famously predicted that one day “some little fat girl in Ohio is going to be the new Mozart and make a beautiful film” with a video recorder. “The so-called professionalism of movies will be destroyed forever,” Coppola enthused. “And it will really become an art form.”

Art form or not, videotape clearly held equal attraction for big-fish studios and tiny-minnow indies, for the same reason: It’s cheap and easy. Forget the fat girl in Ohio — it was the fat cats in Hollywood who saw video as one way to keep spiraling costs down. Once it was digitized — and video was supplanted by computer technology — its aesthetic potential increased exponentially.

Digital image capture started gaining crucial toeholds in the 1990s, when respected cinematographers and directors began to embrace it. It was no surprise that such early technological adopters as George Lucas and James Cameron began evangelizing for digital. But cineastes took more serious note when in 2000 the revered Roger Deakins pioneered the use of the digital intermediate process — whereby a film is finished in digital form before going out to theaters — on no less than the tea-soaked, Depression-era throwback “O Brother, Where Art Thou?.”

In 2007, David Fincher proved digitally recorded images could convey authentic period mood and intensity in his 1970s thriller “Zodiac”; that same year, “Paranormal Activity” digitized the video revolution that began eight years earlier with “The Blair Witch Project,” which ushered in a new era of “found footage” horror films, marked by blurry, blippy, buggy images that intentionally looked cadged on the fly rather than composed. In 2009, “Slumdog Millionaire” became the first film photographed entirely digitally to win a best cinematography Oscar, and “Avatar” changed the 3-D digital-image game forever.

But 2009 was also the year that Michael Mann — known as a bold visual stylist from his work on “Miami Vice” and “Heat” — released “Public Enemies,” about Depression-era gangster John Dillinger. Filmed on high-definition video, “Public Enemies” looked cheap and cheesy, especially in its nighttime action scenes, which possessed the wavy, floaty quality most often associated with daytime television. Mann’s stylized signature seemed to have given way to an anachronistic, pixelated sharpness that took on a smeary quaver when Dillinger and his men were in motion . A year later and several genres away, the romantic-action-comedy “Date Night” suffered from the same problem, with the antics of Tina Fey and Steve Carell often looking as though they had been filmed for a made-for-TV movie rather than a $50 million Hollywood production. If this was “lifelike” HD, give me painterly brush strokes — also known as depth, texture, warmth and translucence — any day.

Still, as disquieting as those misfires were, digital seemed to take a giant leap forward last year, when such films as “Drive,” “Melancholia,” Fincher’s “Girl With the Dragon Tattoo” and the Navy SEALs thriller “Act of Valor” found new saturation, expressiveness, range and precision in digital cinematography. Explaining how he achieved the bright palette and vivid lines in “Drive,” director Nicolas Winding Refn first mentioned getting a really good camera (in this case the Alexa, manufactured by nearly 100-year-old German camera company Arri) and hiring a great digital colorist, who can shape and deepen a film’s look by adjusting color just as lighting electricians contour shadow and light for the same purposes. “The grader is the new gaffer,” Refn quipped, referring to color and light technicians.)

Directors Scott Waugh and Mike “Mouse” McCoy used a Canon 5D digital camera to film “Act of Valor,” much of which was caught in real time on actual SEAL training maneuvers. But there’s some 35 millimeter film in “Act of Valor” as well, and the two were adamant that the video portions look just as rich and textured as the film stock. “Shane has a really good word for it, which is plastic,” Waugh said of cinematographer Shane Hurlbut, describing how video looks at its worst. McCoy added that they fitted the digital cameras with old Leica lenses, which added texture to the images. “They had this 1980s Leica glass that just had this subtlety to it,” he recalled. “All of a sudden we’d found the secret sauce.” When “Act of Valor” was in post-production, the filmmakers took care to turn any “noise” — a static-like pattern that’s a common artifact of filming on video — and into film grain. “It’ll be 35 [millimeter] to 5D in the same scene, and it’s seamless,” McCoy said.

Such directors as Refn, Fincher, Waugh and McCoy are proving that, like all expressive tools, digital is as good as the artists who use it. But even the advances of 2011 didn’t convince film’s high-profile holdouts. Shortly after showing his new film “Moonrise Kingdom” to the press at the Cannes Film Festival on Wednesday, Wes Anderson — who shot the coming-of-age love story in Technicolor, on 16 millimeter film — noted ruefully that this might be his last celluloid endeavor.

Anderson recalled being interviewed by a magazine that regularly publishes grids of what equipment various directors used on their upcoming projects, including the film format. “Every single one of them said HD except ours,” he said. “But I think in two years ours will have to say HD, too. I think this option is disappearing. . . . I don't know. Maybe there’s a great app that can make [digital] look like film, but in my opinion there’s really no substitute.” With Kodak — one of the chief purveyors of film stock — in bankruptcy and processors like Technicolor on the ropes, it’s unclear whether raw film stock will even be an option for much longer.

In December, Christopher Nolan — he of “Batman Begins,” “The Dark Knight” and “Inception” fame — convened some of Hollywood’s most high-profile directors to watch some advance footage of “The Dark Knight Rises.”

He then told them why he’d really called. “The message I wanted to put out there was that no one is taking anyone’s digital cameras away,” Nolan told DGA Quarterly, which covers the Directors Guild of America, in its spring issue. “But if we want film to continue as an option, and someone is working on a big studio movie with the resources and the power to insist [on] film, they should say so. I felt if I didn’t say anything, and then we started to lose that option, it would be a shame. When I look at a digitally acquired and projected image, it looks inferior against an original negative anamorphic print or an Imax one.” (Nolan is just one of many filmmakers who will be seen debating the digital-vs.-film issue in “Side by Side,” a documentary produced by Keanu Reeves that comes out this summer. But it should be noted that he wasn’t above including some snippets of HD video in “Inception.”)

Nolan, Anderson and many of their peers have recently spoken out about feeling pressured by studios to make their films digitally, which is part of a recent push to have every movie theater in the country — not just chains but independents — convert to digital projection. The expensive enterprise is by now almost complete; the average American filmgoer would be hard-pressed to see a movie projected on film today, even if it was originally made on celluloid. (Some predictions have 35 mm film disappearing almost entirely from theaters by 2015.)

On one hand, digital projection is good news, banishing forever the problem of prints that would tear and scratch just a few weeks into their runs, not to mention the scourge known as “under-lamping,” wherein theaters would save money by using low-watt light bulbs in their projectors, resulting in otherwise sparkling movies being reduced to vats of pea soup. (I was once with Oliver Stone before a screening of one of his films in Austin, and he fled the theater just as the lights went down. He knew what kind of visually compromised experience was coming, he explained, and he couldn’t bear to watch.)

But it turns out that digital projection doesn’t guarantee a pristine viewing experience — far from it. At the Maryland Film Festival this month, University of Wisconsin Cinematheque programming director Jim Healy recalled seeing the visually stunning “We Need To Talk About Kevin” on film; when he went back a second time, the theater was showing it on a high-definition Blu-ray disc (an increasingly common practice), but through a non-HD system. The result was dark, dingy and virtually unintelligible, and Healy left after a few minutes. “It just wasn’t the same film.” And don’t get him started on how many times he’s seen a 2-D movie projected on a screen meant for 3-D films, an all-too-common occurrence that results in yet more dark, dingy images.

The digitization of the theatrical experience — whereby audiences are basically watching a DVD on a really big screen — raises more troubling questions for Healy and his fellow exhibitors. “We’re now looking at generations of movie viewers who, if they’re going to cinemas at all, will see stuff digitally projected, and it won’t be too different from what they’re seeing at home,” he says. “That concerns me, because if there’s less and less of a difference, then what’s the reason to keep going out?”

And it’s not just a question of visiting the corner bijou to find fellowship at the altar of celluloid and sprocket holes. As the distinction between film and digitally captured images disappears, so does the notion of the cinematic medium itself. When big-screen movies are made to be seen on iPhones, and the next big holiday-season epic looks more like an NFL playoff game than a composition of discrete and expressive formal properties, our aesthetic expectations aren’t just evolving but eroding.

As the cinematographer John Bailey said to me last year, what’s at stake in these questions isn’t just the evolution of standards or generational tastes, but the very notion of cultural consensus over what the term “film” means. It’s the question of whether a bug should become a feature, and what might be irrevocably lost in the metamorphosis.