JACQUES RIVETTE'S drama "La Belle Noiseuse" shared the bill at this year's New York Film Festival with several other works about art-making of various kinds, continuing a trend among filmmakers to examine the artistic process. Examples include the Chinese epic "Life on a String" and the Finnish drama "Zombie and the Ghost Train," both about musicians, and the French biography "Jacquot de Nantes," a study of the late filmmaker Jacques Demy by his wife, director Agnes Varda.While all these pictures are well worth seeing, "La Belle Noiseuse" stands out as the most impressive. Some moviegoers may balk at its four-hour running time, others at its extensive nudity. But every minute is justified by its thoughtful style and content, and its nudity serves the purposes of high art rather than the low vulgarity that often creeps (or gallops) into conventional movies. Unusually demanding and exceptionally rewarding, it ranks with the most memorable offerings of recent years. The basic plot of "La Belle Noiseuse" comes from a Balzac story called "The Unknown Masterpiece," which also inspired Sidney Peterson's avant-garde classic "Mr. Frenhofer and the Minotaur" in 1949. Balzac's tale concerns a great artist whose masterpiece has lain unfinished for many years, and a woman whose beauty inspires him to take it up and complete it. Also present is a young painter who must grapple with his lover's decision to pose for the long-abandoned portrait. Balzac's story, which has been called an abstract-expressionist parable, warns against the ideal of perfectionism in representational art - an ideal that claims to serve the cause of aesthetic purity, but poses the danger of artistic self-doubt and paralysis. Frenhofer, the central character, has worked to the limits of his endurance in making his portrait an epitome of pictorial magnificence. Yet when the painting is finally seen, it proves to be a maze of self-canceling scrawls and blotches, with just one superbly rendered detail still visible to suggest the mastery it contained before obsessiveness took over the artist's judgment. Mr. Rivette has worked many changes on Balzac's idea, updating the story and giving it a new conclusion that is more optimistic yet also more enigmatic than the original. He has woven elements from another literary work, Ibsen's drama "When We Dead Awaken," into the narrative. And he has added more major characterizations to the plot, transforming Balzac's energetic sketch into a meditative mural that calls for thoughtful contemplation rather than the quick perusal that is sufficient for most movies. It isn't surprising to find Rivette using a literary classic as the starting point for a cinematic adventure. A founding member of the New Wave group that revolutionized European cinema some 30 years ago, he has often turned to great writers for inspiration or material - from Balzac in "Out 1: Spectre" to Racine in Amour Fou" and Thomas Kyd in "Noroit," among others. In every case, the result is less a "movie adaptation" than a wholly original work of art in which Rivette's visual genius plays counterpoi nt to whatever has caught his imagination in the text. RIVETTE'S main interest in "La Belle Noiseuse" seems to be the notion of blurring boundaries between different aspects of artistic experience, thus suggesting that all of art can ultimately be considered a seamless whole. This is implicit in the basic fabric of "La Belle Noiseuse," beginning with the fact that the film itself represents a particularly striking merger of cinema, painting, and literature. It is also reflected in one of Rivette's boldest devices within the movie - devoting much of it to lei surely shots of the painter at work, during which the screen is filled entirely by the artist's hand as it covers a sketchpad or canvas with lines, forms, and colors. Rivette goes even further when he blurs the boundaries between performers in the film: The painting hand belongs to real-life artist Bernard Dufour, while veteran actor Michel Piccoli plays Frenhofer in all other parts of the film. In the same vein, Rivette takes clear pleasure in complementary relationships of all sorts - between reality and make-believe, light and darkness, love and rivalry, drama and comedy, artist and model, the interiors of a shadowy chateau and the expanses of a glorious French cou ntryside. The opportunity to watch a great filmmaker savor and explore such contrasts is one of the chief rewards "La Belle Noiseuse" has to offer. Another is its ensemble of fine performances by a cast including Mr. Piccoli as the painter, Jane Birkin as his wife, and Emmanuelle Beart, best known for "Manon of the Spring," as the model who enters his complex creative world. The film has also been photographed with consummate skill by William Lubtchansky, whose credits range from Rivette's own "Duelle" to Claude L anzmann's documentary "Shoah" and Peter Brook's epic "The Mahabharata." According to a character in the film, the phrase "La Belle Noiseuse" refers to a woman who is both beautiful and difficult to deal with. The film itself fits this description to a degree: It is certainly gorgeous, yet its length and its leisurely pace demand an unusual degree of commitment. It isn't quite a full-fledged masterpiece to rank with Rivette's great "Out 1: Spectre," and those who cherish his usual willingness to take narrative risks may be disappointed with its plot, which is more straightforward than anything he's done since "La Religieuse" some 15 years ago. Yet this straightforward quality is what makes "La Belle Noiseuse" the most accessible Rivette film in decades. It's a truly great achievement, and anyone interested in the art of film should enjoy the challenges it poses.