But usually it's the director. David Lean, Stanley Kubrick, Martin Scorsese, Francis Ford Coppola, Ridley Scott and Peter Jackson are at the top of the list of those who have added value to the novels and short stories they've brought to the screen.

But film for film, it's hard to beat Taiwanese-born director Ang Lee. He's proven a safe bet over the years.

Cultural diversity? He's an expert. In its own cool way, his version of Jane Austen's Sense and Sensibility (1995) was just as agile as his exuberant Eastern fairytale, Crouching Tiger, Hidden Dragon (2000). And he did equally well with Rick Moody's novel The Ice Storm (1997) – sex in the suburbs, 1970s-style – and Annie Proulx's Brokeback Mountain (2005), for which he won an Oscar.

Now he's in line for another one with Life of Pi, Yann Martel's novel about a shipwrecked Indian boy sharing a lifeboat in the Pacific with a Bengal tiger. The clips we've seen are luminously beautiful and James Cameron has added to the hype by applauding Lee's use of 3D.

Books supply the film industry with its protein. Its scouts remain alert to the first whiff of a hit because a film version will be obligatory. Pre-recognition, they call it. The success of the book sets up the buzz and the film steps in to exploit it. As the screen versions of Dan Brown's The Da Vinci Code and its sequel demonstrated, they don't even have to be good. The prospect of measuring your imaginings against those of the filmmakers can be allure enough.

This summer presents a disparate selection. As well as Life of Pi and the latest James Bond and Twilight instalments, we're offered Peter Jackson's new Tolkien adaptation, The Hobbit: An Unexpected Journey, the long-promised screen adaptation of the musical Les Miserables, a new Anna Karenina and the first film to feature thriller writer Lee Child's soldier-turned-crime fighter, Jack Reacher. Already Child fans are expressing their dismay at the fact that the barrel-chested Reacher, who's 1.96 metres tall, is being embodied in the diminutive figure of Tom Cruise.

Like Shakespeare, Dickens, Austen and the Brontes, Tolstoy can bear any number of fresh interpretations, and we've seen a few. Greta Garbo and Vivien Leigh produced Annas. So did Jacqueline Bisset, whose Vronsky was Christopher Reeves. But if that unlikely combo sneaked under your radar, it's hardly surprising. Theirs was a little-seen TV movie. There have also been numerous Russian Annas and a couple given to us by the BBC. The liveliest was delivered by Helen McCrory, whose large, dark eyes and throaty voice helped make her irrepressible Cherie Blair one of the highlights of the Helen Mirren hit, The Queen.

The new Anna is directed by Joe Wright, who filmed the Ian McEwan novel, Atonement, as well as doing the most recent Pride and Prejudice. Both starred Keira Knightley, who, it seems, has become indispensable to Wright when it comes to a spirited heroine who can look superb in period dress. Knightley has a skittish, febrile style and early critical response to her Anna has been mixed. The film itself promises to be spectacular in a highly stylised way. Wright shot much of it on a Shepparton sound stage but this hasn't prevented him making the most of the story's essential aesthetic elements – sparkling snowdrifts, trains billowing clouds of steam, splendid ballroom scenes, deep shadows and sumptuous colours.

He also has a Tom Stoppard screenplay but, oddly enough, it hasn't attracted the same praise as his production design.

Now to Victor Hugo. It would be fascinating to know what he thinks of his great political tragedy's metamorphosis into Les Miserables: The Musical, yet it has taken music and lyrics to extend the novel's life to stage and screen. There have been earlier film versions – the previous one was made in 1998 by Danish director Bille August with Liam Neeson as Valjean and Geoffrey Rush as Javert – but it failed to fire.

Excitement has centred on the new film, based on the musical. Tom Hooper (The King's Speech) directs with Hugh Jackman as Valjean, Russell Crowe as Javert and Anne Hathaway as Fantine. Rather than miming to pre-recorded versions of the songs, they sang live to camera and, judging from clips of Hathaway's heartbreaking I Dreamed a Dream, this bold move has produced dramatic rewards.

The dirtiest word in the adaptation business is "respectable". It followed the Merchant-Ivory team around for years as they diligently transferred the work of E. M. Forster, Henry James and a host of other writers to the screen. And after a while, they couldn't win. Merchant-Ivory had become a synonym for stodgy.

Yet dedicated fans of a novel can get very upset if their favourite bits are excised or tampered with carelessly. Balance is the aim. Casting, too, is crucial. Making a bold move of my own, I'll go so far as to say it's Robert Pattinson's overacting that makes the Twilight movies work.

The Harry Potter films, on the other hand, have a lot going for them. They attracted a string of talented directors but their producers took out insurance by backing up their young leads with a constellation of Britain's theatrical knights and dames.

Peter Jackson was equally canny in casting his Lord of the Rings trilogy and The Hobbit, and David Fincher's American remake of The Girl with the Dragon Tattoo would have been doomed had Rooney Mara's Lisbeth Salander not stood up to the one given us by Sweden's Noomi Rapace.

Films often transcend their source material. Coppola overcame his reluctance to take on Mario Puzo's novel The Godfather and turned it into a film classic. And while there have been plenty of Stephen King adaptations, none has come close to the eccentric brilliance of Kubrick's The Shining. For one thing, it gave us an entirely new concept of the haunted-house movie. No dark corners and rattling skeletons with this one. It had art deco elegance and ghosts who drank cocktails.

The most gifted adaptors are able to expand on their sources. Annie Proulx expressed delight at the way screenwriters Larry McMurtry and Diana Ossana fleshed out Brokeback Mountain. They had turned her "little canoe" into "an ocean liner", she said.

And while Philip K. Dick's Do Androids Dream of Electric Sheep? shares its theme and main characters with Ridley Scott's Blade Runner, the film radically reworks the novel's plot and changes its mood, as well as creating a far more elaborate future world than the one envisaged by Dick.

But no director is foolproof. Kubrick's Eyes Wide Shut made very heavy work of Austrian writer Arthur Schnitzler's novella Dream Story, and Scorsese failed to make anything remotely believable out of Gangs of New York, even though he was working from journalistic accounts that exhaustively documented all aspects of the city's 19th-century underworld, including its vernacular.

Baz Luhrmann, too, is grappling with a slice of New York history as he finishes up his film of The Great Gatsby, which will be with us early in 2013. As well as the passion that F. Scott Fitzgerald invested in the central love story, there's the sharpness with which he scrutinised upper-class arrogance. But we film buffs have a more vital question: Can Leonardo DiCaprio and Carey Mulligan match Robert Redford and Mia Farrow's performances in the 1974 version?

Five of the best adaptations

Gone with the Wind (1939)Two directors worked on Gone with the Wind after George Cukor was fired but producer David O. Selznick called the shots. He cast Vivien Leigh and Clark Gable and made sure Margaret Mitchell’s novel was filmed on a scale that made it  one of the most durable of all classics.

A Clockwork Orange (1971)  Stanley Kubrick’s film of Anthony Burgess’s satirical novel about Alex DeLarge  and his loathesome band of thugs, the “droogs”, is still causing arguments. It leaves you plenty of room to make up your own mind about its moral stance but there’s no arguing its looks or  tone.

The Godfather (1972) How do you turn a commercial property into art? Francis Ford Coppola’s adaptation of Mario Puzo’s bestseller shows exactly how. Coppola transformed the novel’s account of the making of a criminal dynasty into classical tragedy.  Brando and Pacino helped.

Blade Runner (1982) Ridley Scott’s film of Philip K. Dick’s novel is not on the list of historic  greats but it remains one of the most innovative films ever made — a perfect marriage of style and theme. Scott’s bleak vision of the future is underpinned by a poignant sense of emotional dislocation.

Casino Royale (2006) Franchises command most of the top box-office spots, with The Lord of the Rings and the Harry Potter series as historic favourites but I’m choosing my favourite Bond — Casino Royale. Daniel Craig has reinvigorated 007 and in this one, with Eva Green, he’s at his sexiest.

Twitter: @SandraHFilm