Two approaches to biography go on view at Film Forum today with the opening of two films, a short and a feature, each of which treats a titan of 20th-century cinema. Guy Maddin’s “My Dad Is 100 Years Old,” a 16-minute tribute to the master of Neorealism, Roberto Rossellini, opens for “Bergman Island,” a conventional chat-and-stroll documentary about Ingmar Bergman, the 88-year-old director of “The Seventh Seal,” “Fanny and Alexander,” and other art-house monuments. Ostensibly the playful lead-in, the shorter piece not so secretly feels more like the main event.

So much about “My Dad” would seem to bode batty indulgence. As suggested by the title, the actress Isabella Rossellini teams up with Mr. Maddin to mark the centennial of her father’s birth. But the director of pioneering works like 1945’s “Rome Open City” is represented as a disembodied Buddha-belly with a contentious, booming voice. And the cinematic luminaries who “appear” in the film — Federico Fellini, Alfred Hitchcock, Charlie Chaplin, David O. Selznick, even Isabella’s mother Ingrid Bergman — are all performed by Ms. Rossellini, in costume.

Two words should assuage any worries: “Guy Maddin,” the filmmaker who, in 2003’s “The Saddest Music in the World,” outfitted Ms. Rossellini with glass legs and filled them with beer. One of the finest mad-genius silentfilm directors who never was, Mr. Maddin brims with contagious cinephilia, crackerjack visual invention, and careening good humor. Who better to honor a pioneer of cinema in a way that feels less like a school lesson than a weird dream you had last night?

Set in a liminal space resembling a movie theater without the seats, “My Dad Is 100 Years Old” evolves from a series of recollections to a running discussion featuring Ms. Rossellini and the opinionated crew she brings to life. It’s propelled by Mr. Maddin’s nimble hand, but the script was written by none other than Ms. Rossellini herself. Her fond memories of throwing herself on her father’s porcine tummy mingle with debates about whether cinema is entertainment or, as her father had it, edification.

“My Dad” is both, as well as being rather clever. Remembering Rossellini in this way imbues the famously rigorous director with a sweet, paternal feeling. Any pretensions are undercut by the filmmakers’ embrace of humor and a child’s perspective, which acknowledges and excuses the adulation. As Ms. Rossellini says of her talented father, taking refuge from her fears that her memory of him is fading: “I don’t know if you’re a genius, but I love you.”

Call me newfangled, but some similar filter would be nice for “Bergman Island.” With consummate Swedish politeness, the filmmaker Marie Nyreröd draws out the now 88-year-old director as a hypersensitive, raw soul, today placid but with a mess of a personal history. The truth may not be pretty, but Ms. Nyreröd insists on underlining Mr. Bergman’s life as the source material for his the tormented but often selfish characters that populate his work.

In disarmingly intimate interviews, Ms. Nyreröd strolls with the saturnine Swede on the grounds of Faro, his windswept island outpost. Due attention is given to Mr. Bergman’s earliest psychic influences. A beloved mother literally shoved him away, while his brother received a coveted Christmas gift instead of him: a magic lantern.”Could anything be more humiliating than being given a teddy bear?” he now asks.

The documentary continues in this vein, some of the material familiar from Mr. Bergman’s own autobiographical efforts. That apparently includes much of his fictional work: The shattering adultery in 1973’s “Scenes From a Marriage,” for example, drew on the dashing director’s own ignoble affairs. An absentee dad, he dismisses any bad conscience as a comforting affectation, evocative of Erland Josephson’s characters in “Scenes From a Marriage” and 2003’s “Saraband.”

Ms. Nyreröd elicits some beautiful musings on the ambient spirituality Mr. Bergman feels living on the island and on religion’s role as a communion with humanity. But the revelations about his peccadilloes forget that what’s great about his work is not the traceable inspiration he drew from life, but the results, namely the films themselves.

The limits to Ms. Nyreröd’s approach emerge in Mr. Bergman’s reaction to persistent questions about his relationship with the two stars of 1966’s “Persona,” Bibi Andersson and Liv Ullmann. Voluminous till then, he stops short, suddenly tongue-tied. It’s an undeniably striking moment but, held too long, feels like a TV-interview “get,” part of a provincial dialogue that remains disconnected from his work.

Any Bergman fan would have to confess to a bias against demystifying an idol. But even newcomers might feel bewildered (or vaguely embarrassed) when Mr. Bergman actually produces a scrawled list of the “demons” that haunt him, including disaster, fear, rage, grudges, disorder, and nothingness.

“Bergman Island”is eminently watchable and always feels quite civilized. But maybe the ennobling, humanizing potential that Rossellini’s gut sees in cinema requires a bit of mythos and whole a lot of the movies themselves.

Through December 19 (209 W. Houston St., between Sixth Avenue and Varick Street, 212-727-8110).