Taking a little too much off the top

“Barbershop,” which premieres Sunday night at 10, is Showtime’s sitcomization of the film franchise of the same name. It’s an obvious move -- the films on which it’s based are half-sitcom already, taking place mostly on a single set (meticulously recreated for television) full of colorful characters who talk a lot. But though the TV version catches some of the tone and replicates the topicality of the big-screen originals, and shares executive producers, it lacks their grounded reality -- not too surprising, really, for a work of fiction based on a work of fiction -- as well as their warmth.

It’s a thankless task, stepping into the shoes of a hit movie -- and not just a hit movie, but a movie whose success was based as much as anything on chemistry and tone. Everyone seems to be working a little too hard here to let you know they’re having as good a time as their big-screen predecessors. And it doesn’t help that the first couple of episodes warm over incidents from “Barbershop 2,” as, against his better judgment, shop owner Calvin Palmer (Omar Gooding in for Ice Cube) disastrously hires a relative of his wife, and a new franchise appears to threaten the peace of the neighborhood. The details in each case are different, but the situations are close enough to suggest that someone in quality control was asleep at the switch.

Where Ice Cube played Calvin with depth and seriousness, as conceived here -- veteran TV writer John Ridley writes and directs -- he is more of a typical sitcom lead, hapless and put upon and at the mercy of the eccentrics around him. More critically denatured is Eddie (Barry Shabaka Henley in for Cedric the Entertainer), the old barber whose role in the film as voice of experience and sacred-cow slaughterer drowns here in nonsense and vulgarity. Other characters fare as badly: Aspiring politician Jimmy (Leslie Elliard) becomes a fast-talking, self-promoting jerk. And Calvin’s wife (Anna Brown) goes from being a voice of reason to something of a fool.

Where the films embody the qualities they espouse -- that is to say, they’re films about decency and respect that are themselves decent and respectful -- the sitcom wants to push buttons. (This is fairly emblematic of Showtime’s original series.) Its language is rougher than the originals’, and it’s more insistent about sexual content, as if the medium of premium cable actively demanded undeleted expletives, occasional hits of female nudity and long routines about oral sex. The movies, by contrast, benefited from their PG-13 ratings; their success was rooted in their restraint.

Still, it’s not the worst half hour on television, and among sitcoms fielded by Showtime it ranks very near the top. The performances are generally good, if the parts tend toward caricature, and there are some laughs along the way. (A guest shot by Page Kennedy as a wannabe rapper -- “There ain’t no CD in there,” he tells Calvin, handing him a jewel case, “I couldn’t afford to press ‘em up but it’s a ill box, though, right?” -- is worth noting.) Not the least thing to be said in its favor is that it’s a show about ordinary working people, and a few not-working people -- a demographic that TV has largely abandoned on “black shows” and “white shows” alike. The medium (like the nation, I suppose) is gripped with dreams of upward mobility, and in such a context, it’s refreshing if not radical of “Barbershop” to suggest that money isn’t everything.

*

‘Barbershop’

Where: Showtime.

When: 10 p.m. Sunday.

Ratings: TV-MA (may be unsuitable for children under age 17)

Omar Gooding...Calvin Palmer

Gbenga Akinnagbe... Yinka

Anna Brown...Jen Palmer

John Wesley Chatham...Isaac Rosenberg

Leslie Elliard...Jimmy James

Barry Shabaka Henley...Eddie

Toni Trucks...Terri Jones

Dan White...Romadal Dupree

Executive producers: John Ridley, Robert Teitel, George Tillman Jr., Ice Cube, Matt Alvarez. Writer and director: John Ridley.