At the Corcoran last night, as the TV crew moved in and the lights began to glare, Peter Max, an artist who is famous for being famous, stopped smiling for a moment. His eyes went all sincere. "I've really changed," he said.

Six of his new paintings were on the wall behind him. His work is just as facile, just as colorful and friendly, and as fatuous as ever. But the subject matter of his art is not what it once was.

Once upon a time, in the last commercial blooming of the flower-power '60s, his images were everywhere -- on ashtrays, washcloths, T-shirts, clock faces and posters.His stars and doves and rainbows, and his wizards in flared trousers, appeared on the covers of Life and Time and Business Week and 40 other magazines. Peter Max was pop. Peter Max was with it. Critics hinted darkly that his corny, cosmic fantasies were full of coded references to decadence and drugs, but his public was not frightened. Neither was Ed Sullivan. Neither was GE. Peter Max was fun.

His life abruptly changed, he says, in 1972. He was vacationing in Mexico -- with his entourage of 28 -- in John Wayne's handsome villa near the shores of Acapulco when he saw the light: "My art had become business. I loved it for a while. Objects worth, I'm told, a quarter of a billion dollars were produced to my designs. I'd seen production lines a quarter of a mile long grinding out my plates. Depression hit me all at once. Suddenly I realized just how much I missed pure painting. I came back to New York, to my 18-room studio-apartment -- it overlooks the Hudson -- and told my staff to cancel all my design contracts. I went into what I describe as 'creative retreat.'"

When Max at last emerged, his hard edges had gone soft, his brushwork had grown brushier, his imagery had been altered. His art no longer hymns the old saccharine psychedelia. The Max of 1981, so his flacks will tell you, is, instead, "America's own most patriotic artist."

More than 100 million people, braced for thorough searches by U.S. Customs officers, have been welcomed to our borders by Peter Max's posters. He has designed U.S. postage stamps. And on July 4, 1976, he painted his first eight-foot canvas of the Statue of Liberty. He's been at it ever since.

On July 4, 1977, he painted two Liberties. A year later he made three. The next Fourth he did four. Last July 4, on the green grounds of the Reagan White House, while the president, his wife, and many others watched, Max completed six. He'd done another set of Liberties for President Jimmy Carter. They were sold to bring in money for Carter's last campaign. Peter Max is not disloyal. "I like presidents," he has said.

The latest of his Liberties, those he did last month, go on public view at the Corcoran today. The Corcoran of late has become a sort of party room for its neighbors at the White House and for corporate American. "I met Peter at the White House and the White House called to ask if we could show the pictured he had made there," said Peter Marzio, director of the gallery. "I like Peter Max. I don't mind social events. This is not an art event as much as it's a party. I figured, 'Well, why not?'"

"I loved painting at the White House," Max said. "I love to work like that, creatively, spontaneously, with crowds of people watching. These paintings are so free. I create them as I paint them. I used to get so tired of sticking to a plan."

America's own most patriotic artist will not keep all those canvases. He is giving most away. One will go to Ronald Reagan (who has yet to pick his favorite), one will go to New York's Mayor Koch, others will be given to Canada and Mexico. And one will be presented to the government of France as a king of thankyou for the giant statue that the French erected in Manhattan's harbor 97 years ago.

Has Peter Max at last given up on commerce? Has he cut his ties to giant corporations? Is it just for art's sake that he makes his art?

Well, not exactly.

New York Air paid for last night's opening and a company called Korbel donated the champagne.

"Hi," said Peter Miller. "I'm Peter Max's agent. Make sure you say that Data General Corporation, via the auspices of Peter Miller, paid for all the beautiful Peter Max-Corcoran Gallery-Statue of Liberty posters. We will probably be publishing at least 1,000 sets.

"One hundred of those sets will be given to the White House, for Christmas gifts," said Miller. "Data General will keep 250 portfolios. They'll give them as rewards to the successful salesmen in their Million Dollar Club.That takes care of 350 sets. They're worth about $700 apiece. Peter Max will keep the rest."

Max calls his Liberties "labors of love."

His posters are regularly on sale in about 150 galleries. His canvases, says Miller, may be worth as much as $75,000. The television crew at last night's celebration was hired by the artist to record his own career.

Max is 43. He was born in Germany and lived in China for a while before coming to this country when he was 16. "Even in the '60s, when my businesses were booming, I never saw myself as a commercial designer," he says. "I've always been a painter. My art took me into business, but I didn't want to stay there. I want my success to be in the world of art."