The 15th New York Film Festival, currently in progress at Lincoln Centers's Tully Hall, is a tribute, among other things, to the seemingly limitless expressive range of motion pictures. It would be hard to imagine a more drastic set of contrasts than those offered by three of the features shown so far.

Francois Truffaut's "The Man Who Loved Women," the late Pier Paolo Pasolini's "Salo," and Werner Herzog's "Heart of Glass," have one thing in common besides the medium they share - they are all about obsession. Beyond that, they are as different in tone, method and effect as imagination can conceive.

Each film reflects both the personality and the artistic milieu of its creator. Truffaut's warm, funny, touching film is about an obsession with romantic passion. Pasolini's excruciatingly perverse swan song (he was brutally murdered before its release), political in intention but visceral in impact, examines the effects of an obsession with the ultimate extremes of sexual sadism. The Herzog, mirroring the parched intellectualism of the new school of German cinema, seems to be a parable about obsession itself, though it meanings are so shrouded in obscrurity that any interpretation is bound to be conjectural.

The Truffaut is the only likeable one among them, not only because his subject matter is the more appetizing, but because Truffaut is an invariably sympathetic filmmaker, where the other two are more concerned with provocation than entertainment. In any case, Truffaut has given us one of his most perfectly realized explorations of the ways of the human heart in "The Man Who Loved Women."

Most men have trouble getting women off their minds.Bertrand, Truffaut's hero, never bothers to try. A scientist by profession - we see him carrying on experiments in wind tunnels and simulated waterways - he is so consumed by his visions of amorous liaison that he devotes virtually every waking and sleeping moment to planning his campaigns of conquest. In almost every woman he encounters he finds adorable traits, and each sets his mind to fantasies of courtship or seduction. Unlike most civilized males, however, he carries them out, or attempts to.

The paradox of Bertrand is that no one experience ever seems to engage him fully. Despite the intensity of his devotion to females, he can never give himself to a relationship with one of them unstintingly. As much as he prizes love affairs, he values his autonomy even more. The passion that drives him to exclude everything from his life but women also requires of him, it seems, the liberty to love all of them equally. In one of the most affecting scenes of the picture, he has a passing meting with an old flame, alluringly played by Leslie Caron, who onece melted down this barrier, but too late. By the time Bertrand was ready for a full commitment, her own feeling had waned, cooled by his habitual defenses.

Though Truffaut protested in a festival press conference that Bertrand, as sensitively acted by Charles Denner, was not supposed to have any universal application to maledom, the film clearly shed light not just on one man's mania but on the vagaries of romantic love in general.

"Salo" sets out to be a parable of the human condition from the outset. Maybe that's one of its troubles; the human traits it considers are never placed in any emotionally credible context of individuals. The characters of the film are plainly polemical constructs, and in fact, their all too patent phoniness deprives Pasolini's theorizing of any potential force. The filmmaker, by his own testimony, was trying to draw parallels between sexual depravity and political evil; but it is hard to take the politics seriously when the villains of the drama are just so many halloween specters with makeup.

The picture's vaunted horrors - the scenes of debauchery, torture and nauseating perversions - are probably no raunchier than those perpetrated in our contemporary spate of porno and cruelty epics; but there are more of them per scene, probably, than in even the crudest exploitation flicks. And Pasolini was a master at projecting an aura of terrifying bestiality.

The orgies and torments of "Salo" are plainly simulated, however skillfully. But even if they had not been, the puerility of the drama in which they are imbedded would have made them appear ridiculous rather than revolting, in the final analysis.

Facism is obscene, and that was to be Pasolini's point; but turning it into campy idiocy proves only the impotence of the filmmaker's esthetics.

The Herzog is parable, too, but about what it's hard to say. In often haunting images and beautifully muted photography, a story is told of a primitive mountain village where a special kind of ruby-colored glass is manufactured, until the man who knows the secret process dies.

Thereafter, the factory owner, half a madman to start with, goes all the way beserk in the effort to uncover the mystery of the glass, committing murder and burning down the factory in the bargain.Wandering through the plot is a herdsman soothsayer, who foretells all this and much else of the future as well, including the end of the world and a new beginning.

On second thought, "Salo" and "Heart of Glass" do have something else in common besides obsession - the one is revolting and the other inscrutable, but both are about equally tiresome.