Why love a dark film?

I recall a droll cartoon from The New Yorker. Outside a Manhattan cinema a line of customers queue up to buy tickets for the latest Ingmar Bergman film while, simultaneously, the previous screening's audience shuffle out of the auditorium into the street. Studying their uniformly haggard features and heads practically bowed in despair, one queuer turns to his companion and remarks brightly, "Mmm, looks good!"

There, pithily encapsulated, is the currently received image of Bergman's films - austere, feel-bad movies, which we go to not because they represent anybody's notion of an entertaining evening out, but because we persuade ourselves that a regular dose of pessimism is bracingly good for us, almost therapeutic.

With stark, sweaty candour Bergman confronted head-on the sort of themes that other film-makers either prettified, sensationalised or shunned altogether: death, disease, impotence, humiliation, perversion, solitude and, supremely, the absence of a God who declines ever to make eye contact, as it were, with His own creations. A kind of ne plus ultra or perhaps nadir (depending on how attuned you are to his terminally bleak sensibility) was arrived at with Winter Light, made in 1963, in which he treated eczema, of all ungrateful subjects for a movie, as an existential condition.

Bergman, now 84, has just announced his retirement from both film and theatre. It is not his first such final bow, as it happens (way back in 1982, Fanny and Alexander was supposed to be his last movie but was followed by three more). This time, however, it would seem to be the definitive one.

Given his widely perceived image, we shouldn't be too surprised that his twin swan songs are a film with the melancholy title of Saraband, shot for Swedish television but due to be screened theatrically elsewhere, and a revival of one of the glummest plays in the repertoire, Ibsen's Ghosts, which is being staged for just four performances at the Barbican (ending on Sunday). Even for his fans, the notion of Bergman actually making us laugh is a joke in itself.

Yet, amazingly, such was not always the case. In the Fifties and Sixties, when his reputation was at its height, Bergman, like that other notoriously gloomy Swede, Greta Garbo in Ernst Lubitsch's Ninotchka, did make audiences laugh - laugh aloud and laugh a lot. Hard as it may be to believe for those familiar only with his relentlessly pessimistic late work, he was actually responsible for a cluster of the cinema's most sparkling comedies.

The best-known, the best-loved, and the only one whose title continues to ring a faint bell outside of movie-buff circles, was Smiles of a Summer Night, which was awarded a Special Jury Prize at the 1955 Cannes Film Festival.

An elegantly rococo, seriously funny comedy of manners, a Bergmanesque bergamasque set during a licentious house party at the end of the 19th century, it was labelled by just about every critic with the overused, but for once not abused epithet, "Mozartian". (The few critics to whom it didn't occur to call it Mozartian called it Shakespearean instead.)

Not only did Smiles of a Summer Night enchant cinema audiences, at a period when there wasn't quite the ingrained resistance to haute culture that such a film would nowadays encounter, it was adapted as a stage musical, A Little Night Music, by Stephen Sondheim and served as the inspiration (to put it politely) for A Midsummer Night's Sex Comedy, a surprisingly crude knockabout farce by that lifelong Bergman admirer and imitator, Woody Allen. For several years thereafter, Bergman would regularly alternate between comedies and dramas. Lesson in Love, for example, boasted the kind of cute plot premise that Hollywood producers (or reproducers) now routinely snap up in order to turn out a fluffy English-language remake starring, say, Richard Gere and Meg Ryan: a successful gynaecologist and his wife test their mutual marital fidelity by pretending to be strangers to one another.

The Devil's Eye (its title apparently derives from the Swedish proverb "A faithful woman is a stye in the Devil's eye") was one of the most inventive of the cinema's umpteen treatments of the Don Juan myth. All These Women was a stylised satire on the pesky critical establishment that had been snapping at the director's heels almost since his debut.