This is the time of year when film critics feel like they’re trapped in the old movie “Altered States.” They must instantly turn away from the cultural conceits of the Cannes Film Festival, where they lectured us as to why Lars von Trier should really be taken seriously, to reviewing summer movies about Terminators and Mutants.

Hence for the next few months, we should expect to see an onslaught of critical essays asking, “Who killed independent film?”

It’s a legitimate question, albeit a rhetorical one. The so-called specialty film business isn’t dead, but it’s heading for intensive care. Thus far the sector has generated only one third of last year’s revenues and there are no signs of imminent recovery. Meanwhile, box office in the popcorn picture business is up an astonishing 16%.

Part of the problem stems from corporate politics. Warner Bros. and Paramount have shut down their specialty units while Fox Searchlight has installed a new top management team. The Miramax share of the specialty market has dropped from 20% to 12% over the last three years and the company seems to be changing its direction.

Obviously the worldwide credit crunch is also responsible for reducing the flow of art movies and distribution outlets are being choked off. As a result, specialty companies seem to be increasingly dependent on a genre best described as the “celebrity art film.” A picture gets made if a star is attached.

Hence, “My Sister’s Keeper,” a poignant affliction film, gets funded because Cameron Diaz wants to star in it. The same for Julianne Moore in “Blindness” and Charlize Theron in “Sleepwalking.”

Now, I have great respect for actors who want to “stretch,” even if it means a smaller paycheck, but here’s the nasty reality: The most interesting specialty movies tend to emerge from a filmmaker’s appetite rather than a star’s. To pick a too convenient example, “Slumdog Millionaire” was intriguing because of Danny Boyle’s take on the material — and it had a no-name cast.

In some cases, the presence of stars has had the effect of expanding budgets beyond the point of reality — Angelina Jolie in “A Mighty Heart,” for example. Arguably, “State of Play” would have been a more interesting, and potentially profitable, project had it been shot on a smaller scale — without Russell Crowe.

At Sony Classics, Michael Barker and Tom Bernard have run their shop with a stern fiscal discipline, but they, too, took a flyer on a star vehicle last year, “Rachel Getting Married,” starring Anne Hathaway. The movie was far more costly than their usual fare, but they got away with it because the Jonathan Demme-directed film was quirky and original.

The terrifying truth about the specialty film business is that its two most important ingredients are artistic risk and fiscal caution. There’s no such thing as a “safe” subject for an art film. And the most successful producers have been the most tight-fisted.

A number of companies are presently defying these precepts by producing films in the $30 million to $50 million budget zone that are neither art films nor franchise films. Given the erosion of the DVD business, these projects would seem to be even scarier than in past years, and the presence of a star won’t mean that Wal-Mart will look more kindly on it.

What all this means for the critics in Cannes is that the supply of gritty, original fare — the counterprogramming that makes the summer season bearable — may be skimpy this year. A few critics may even look back longingly on Lars von Trier.

No, that would be pushing it.

A real ‘Museum’ piece

Cinephiles complain there aren’t any good art movies around. They’re ignoring the most expensive art movie ever made, “Night at the Museum: Battle of the Smithsonian.”

Sure, the title may sound klutzy, but consider the following: Here’s a movie in which great paintings come to life. Historic figures utter wise epigrams. And the whole movie takes place in a museum.

Most important, this is a film that displays a truly surreal sensibility in that it has no tenable plot. Not even a basic hook, like the first “Night at the Museum.” Which is all the more surreal, because the sequel must have cost $150 million or thereabouts. (I didn’t ask the studio, Twentieth Century-Fox, because, like all studios, it slavishly protects and distorts its numbers.)

So while all those critics are in Cannes searching for art, I managed to find it at a screening on the Fox lot this week.

But here’s the important part: There are strokes of magic in the second “Night at the Museum.” Shawn Levy is a fabulously talented director and Ben Stiller has abandoned some of the forced mannerisms of his earlier work. He seems totally at ease in this film and so does Amy Adams who, as Amelia Earhart, does a superb turn as a Katharine Hepburn type.

Also performing excellent bits are Hank Azaria, Robin Williams, Christopher Guest and Ricky Gervais.

I’m not going to ask whether it makes sense to shoot a sequel that has no plot. Let’s just say I admire the Fox production mavens for investing so much in a thoroughly surreal work of art.

Besides, the first go-around grossed $574 million around the world. So chances are the sequel will be the most successful art movie of all time.

OK, maybe not really an art movie.