With a bid of $104 million, a painting called "Boy With a Pipe" ("Garcon a la Pipe") by Picasso recently became the most expensive art work ever sold at auction. What makes an art object worth that much? An exhibition at the Getty Center in Los Angeles examines the question.

How much is any painting or sculpture worth?

Gail Feigenbaum, associate director of the Getty Research Institute, says there is no simple answer to the question.

"There's a network of people who are involved in the very complex negotiations that set a monetary value on a work of art," she said. "And this would involve the critics, scholars, experts, and the dealer. And the dealer has a role in promoting an artist and supporting an artist, who has no public."

A Getty exhibition called The Business of Art examines this process.

In Los Angeles, gallery owner Irving Blum helped introduce pop icon Andy Warhol to the public, holding the artist's first solo exhibition in 1962. Ms. Feigenbaum says other dealers and gallery owners have served a similar function.

She says in medieval Europe, artists turned to wealthy patrons who commissioned works of art, but by the 16th century, some artists worked on speculation: they created works of art, then tried to sell them. In southern Europe, the shift is seen in a merchant who sold works by the Italian painter Caravaggio.

"This particular man identified himself as a reseller of second-hand goods," Ms. Feigenbaum said. "And we know that he sold works of art."

In Northern Europe, the development of an art market was tied to merchant networks.

"The international merchants, the ones who have outposts in Brazil and in the Indies, who are buying and selling everything," she said. "The international trade networks also involve luxury goods, exotic goods. A good example is the Fugger family of merchants from Germany."

The German family became major distributors of international art works.

By the 18th century, dealers emerged to advise wealthy clients, and secure art works for them. In the process, some made a handsome profit. They were, the art expert says, only a step removed from the sellers of second-hand goods of earlier centuries.

The Los Angeles exhibition is drawn from the Getty's collections, and among its offerings, it provides a glimpse into the world of Joseph Duveen, the British-born dealer who sold art to American millionaires in the early 20th century. He was perhaps the best-known art dealer ever.

Mr. Duveen could create a swirl of publicity around a work of art, as he did around a painting that he had acquired for the Huntington Library in California. It was the noted "Blue Boy" by Thomas Gainsborough.

"He brought it to the United States, and he created a kind of sensation around it. He showed it in his gallery, charged admission for it, and a number of directors of important museums wrote to Duveen to ask whether the Blue Boy could perhaps be exhibited at their museum, at the National Gallery, for example, before it went to its final home in the Huntington [Library]. And Duveen was very careful to say, no, it couldn't. The only place you could see it would be at Duveen Gallery."

Through letters and documents, the exhibition chronicles such stories.

In the age of mass media, the promotion of art and artists has been taken to new levels, says Getty Research Institute Director Thomas Crow. He says a 1949 magazine story on artist Jackson Pollock signaled the change. Displayed with vivid photographs, the story portrayed the artist as a celebrity.

"There he is standing against one of his paintings that was 18 feet [five meters] long, spread across two whole pages of the old Life magazine, which practically everybody in America received on a weekly basis," he said. "And it asked the question, "Is Jackson Pollock the Greatest Living Artist in America?" And no one had heard of Pollock, outside of a small circle in New York at that point."

Pollock soon became one of the country's most famous artists.

Mr. Crow says scholars, critics and dealers will always play an important role in setting the price of an art work. And a wealthy collector must be willing to pay the price. Good publicity, he adds, can always boost the value of a work of art.

The exhibition The Business of Art: Evidence from the Art Market, will be on display at the Getty Center in Los Angeles through June 13.