MOVIES : Cineastes, Go Home : As thousands of visitors prepare to invade the normally quiet Riviera resort, the typical <i> Cannois </i> wishes they wouldn’t.

The giant movie screen at the Louis Lumiere Auditorium, the heart of the world’s best-known film festival, was dominated the other day by a full-color drawing of a clogged artery and accompanied by the solemn speech of an American cardiologist.

But, as the doctor addressed a small, sleepy audience of medical colleagues, dozens of technicians were working elsewhere in the nine-level Palais des Festivals, setting up screening rooms and testing 25 film projectors.

All across Cannes, in fact, preparations were under way for the 48th Cannes Film Festival, which opens Wednesday.

In the center of town, the 150-member police department was making room for 3,000 extra officers, many of whom will be on the lookout for professional pickpockets. (Last year, 20 pickpockets were arrested and held in jail until after the festival. Some are expected back.)

On the narrow streets of Cannes, boutique owners were sprucing up their windows and food merchants were placing orders for large amounts of everything from lobster to foie gras.

The grand 1920s-era hotels that form an arc along the waterfront were deep in preparations for the big welcome, having concluded their annual competition for the opportunity to play host to the biggest stars.

At the Majestic Hotel, across the street from the Palais, workers were redecorating many of the 290 rooms and installing 40 fax machines and 150 extra phone lines for the arrival of the film world’s movers and shakers. And the hotel management was expecting a 30-yard-long catamaran to be anchored at its seaside dock.

“In the hotel business,” said Gerard Yvos, the tall, elegantly dressed hotel manager, “the difficult thing is to fill the hotel. When it is full, there is no problem.”

On the beachfront walkway known as the Croisette, Rene Rovary was preparing for the crowds of movie fans who will gather, shoulder to shoulder, for a glimpse of their favorite stars. Rovary has run a food stand on the Croisette for 20 years, selling pastries, coffee and pain bagnat , the popular sandwich of tuna fish and anchovies.

“The festival is really the beginning of our season, and it’s important for all of us,” Rovary said. He and his family planned to be on the job until midnight every day of the festival.

“I love to see movies,” he added, “but I see them after the festival.”

Getting ready for the film festival has become almost routine in this pretty city on the Riviera. Technicians at the Palais des Festivals, the site of 150 conferences and festivals annually, have worked as a team on the film festival for years.

“You always get a little nervous before the festival,” said Dario dell’Antonia, the city’s director of tourism, “because you never know for sure if everything will work.” But, he added with a relaxed shrug, “we’ve been doing this a long time.”

The major concern every year is security. Serious threats to actors and actresses are rare, though the crush of the crowds can be frightening for some. But they all want plenty of high-profile protection.

“That, too, is part of the show,” one official explained.

About 28,000 journalists and film industry people are accredited by the festival organizers, and at least that many more visitors are expected from elsewhere in France.

Few of those “inside foreigners,” as local officials call them, will see any of the 53 films being screened. But they make the annual pilgrimage for the outdoor spectacle, the topless women on the beach and the famous actors, directors and producers walking up the steps to the Palais des Festivals.

The typical Cannois , though, doesn’t pay much attention to the festival, viewing it as a two-week aberration of traffic jams in an otherwise quiet town.

“People really don’t give a hoot about it,” said Francois Rosso, bureau chief for the Cannes office of the regional newspaper Nice Matin. “They are happy enough that it happens here, but if someone took it away it wouldn’t be a catastrophe.”

The Cannois like to point out to visitors that there are two Cannes. This may be, for two weeks a year, a loud, lascivious tart, playing to the world’s cameras in the highly hyped film bazaar. But for the remainder of the year it is a quiet, pristine resort, a haven of wealth, conservatism and discretion where stars walk unremarked and unguarded.

“Life here is pretty much like everywhere else in France, only more pleasant,” said Dell’Antonia. “It’s only once a year that the city becomes a playground, a stage.”

In fact, Cannes has been more obsessed in recent weeks with the presidential election campaign, which ended last Sunday, than with the opening of the film festival. And local tongues have been wagging not about the stars who will soon strut on the Croisette but about the city’s popular mayor, Michel Mouillot, who was convicted last month of receiving embezzled funds.

Although Mouillot’s conviction, during a corruption trial in Lyon, legally prevents him from running for reelection in June, he plans to do just that by stalling the legal process with an appeal. And he will probably win reelection, reflecting Cannes’ peculiar sense of civic pride.

“People here see Mouillot’s troubles as an attack on Cannes,” said journalist Rosso. “It’s like we’ve been attacked personally by this court up north in Lyon. The judges said he was guilty, but people here aren’t so sure.”

Besides, colorful politicians are part of the charm of the Cote d’Azur. Last summer, when the mayor of St.-Raphael banned topless women from stores and streets, he told one newspaper: “It’s fine if it’s a pretty girl, but a fat old lady with flesh hanging all over the place . . . this needs some correcting.”

And, in a book on the private lives of politicians in France, Mayor Mouillot himself explained that when he first meets a woman, “I try to look at both her eyes and her breasts at the same time, which requires a very quick look.”

But such remarks are hardly an offense in Cannes, where deposed Haitian dictator Jean-Claude (Baby Doc) Duvalier was welcomed at the finest establishments until his money ran out.

Mayor Mouillot is widely admired here for his ability to attract the tourism business, which is the city’s lifeblood.

The Palais des Festivals is the site of car-launchings, art exhibits and a host of conventions, from hairdressers to pharmacists. But one-third of all the francs spent by tourists in Cannes come during the 11 days of the annual film festival.

“Our festival is growing and becoming more and more important,” explained Gilles Cima, a handsome, deeply tanned real estate agent who is also the deputy mayor in charge of tourism. “Each year, for two weeks, we are the capital of the world.”

Local lore places the birth of Cannes in 200 BC, shortly before it was overrun by Roman troops and turned into a trading post for the empire. But its birth as a tourist destination came in 1834, when Italy closed its border for fear of an epidemic of cholera in Northern Europe. One of those turned back was Lord Henry Brougham, who found a place to stay in Cannes.

Bewitched by the city, he built a residence here, and within two years all of London high society came rushing to help him open his new estate, making Cannes the new playground of the aristocracy.

On Sept. 1, 1939, the first international film festival opened here. Although the city fathers liked films, their main goal was to lengthen the summer tourist season. But it closed a day later with the outbreak of war and did not return until 1946.

But it wasn’t until one day in 1954 that the festival gained its worldwide fame as an intoxicating mix of sex and cinema.

The authors of “Hollywood on the Riviera,” an exhaustive 1992 history of the festival, say the exact moment came when a young French actress took off her bikini top and embraced Robert Mitchum. The resulting photographs appeared worldwide, and, the book says, “the international definition of Cannes was permanently sealed.”