Michelangelo Antonioni, director of some of Italian cinema’s most iconic films, sits in a wheelchair, staring at a sheet of white paper on a paint-spattered easel. At first nothing comes: then the red pen in his left hand moves slowly, making a loop, and then faster: a series of swooping curves, some jagged edges.

He pauses, while the two female art students who will shortly transform these lines into a painting, using bright acrylic colours chosen by him, hover encouragingly at his elbow. Then another series of intersecting loops. He sits back and looks at us wordlessly, a gleam of triumph in his eyes: another Antonioni masterpiece.

Antonioni (“Il Maestro”, as his admirers call him) turned 94 last week, and to celebrate, an exhibition in Rome, Silence in Colour, is showing more than 100 of his abstract paintings, sketches and sculptures to remind the world that, as well as his long career as a film director, with movies such as L’Avventura, Red Desert, L’Eclisse and Blow Up, he is also an artist.

Antonioni has barely been able to speak since he suffered a stroke in 1985, and paint is his way of communicating. He has not given up cinema: in 1995 he made Beyond the Clouds (Al di la delle nuvole) with Wim Wenders, and he directed a segment of the episodic movie Eros, called The Dangerous Thread of Things, which arrived in British cinemas last month.

His dreamlike films of alienation and spiritual malaise were always directed with an artist’s eye, from the island landscapes of L’Avventura to the industrial Ravenna of The Red Desert and the North Africa and Spain of The Passenger (Professione: Reporter). The critic Roland Barthes once compared the visual effect of an Antonioni film, with its bright splashes of colour, to the paintings of Braque and Matisse.

“When he was making The Red Desert in 1964, his first colour film, he put all the colours down on paper before he started shooting the film,” said Enrica Fico Antonioni, who married Antonioni the year after his stroke. “In a way, he ‘painted’ the film.”

When we met at his airy studio high above a bend of the Tiber in the Tor di Quinto district of Rome, I asked Antonioni if he thought he would be remembered as an artist more than a director. He smiled, and beckoned to Enrica, who speaks for him.

“He has always said, very firmly, ‘I am not a painter!’ ” she said. “But lately it has been his language, and it will be the legacy of his years of silence. He may not be able to speak, but he has used even deeper methods to express himself. Words are not the only way of communicating — in fact they are perhaps the least important way.”

Enrica, who is herself an artist, last year made a documentary about Antonioni the painter, With Michelangelo, which will be shown in Rome to coincide with the exhibition, together with a retrospective of his films.

Antonioni is surrounded by devoted women, including Enrica and his two assistants, Monica Dabbicco and Alessandra Giacinti, students from the Rome Academy of Fine Arts. His most famous female muse was Monica Vitti, star of the great trilogy L’Avventura, La Notte and L’Eclisse (as well as of The Red Desert). In the early years of his fame he lived with Vitti in the flat below (now sold), which was linked to the studio by a spiral staircase. Even at that time he painted, often climbing the staircase to the studio at night. He still prefers to work when it is dark, Enrica says, since the bright Rome light troubles his eyes.

Antonioni started with watercolours and collages: hanging in the studio is a small early work from his 1970s series The Enchanted Mountains. He and Enrica have a house in Umbria, and her film shows them driving through the mountains, often in the rain, looking for landscapes. “The funny thing is he is still looking for film locations, too — the right window, the right door for a scene in his mind.”

He draws with his left hand because of the stroke, using charcoal, pencil or felt-tip pens, tracing the outline which will then be coloured by his assistants. He works meticulously, starting with a single colour and building slowly into a kaleidoscope of bright, swirling, dense paint. He is influenced by Picasso, Bacon, De Chirico, Léger, Lichtenstein and Mark Rothko, all of whom he once collected (he sold his collection after a burglary in which thieves also took his 1995 Oscar for a lifetime’s achievement in cinema).

But his vision is his own. “He always knows exactly what he wants,” Enrica says. “When he was directing, it was just the same. He has incredible artistic intuition.”

Il Silenzio a Colori (Silence in Colour) is at the Tempio di Adriano, Piazza di Pietra, Rome, until October 22, www.rm.camcom.it