There is little in the world of cinema that gets the blood boiling or the nostrils flaring quite like the argument that can develop over literary adaptations. Rarely do adaptations meet the finicky criteria of those who come to the screen via the page. “It wasn’t as good as the book,” you’ll often hear. However, at the core of this complaint is a snobbery that perfectly encapsulates the continuing disability of both the wider public and more narrow-minded bibliophiles to accept cinema as an expressive and technical art form, as well as a generator of filthy entertainment lucre.

The fact of the matter is – taking a step back – that judging a film on the basis of the source material is rife with prejudice and misconception. Cinema is an entirely separate medium that should be judged on its own terms, and this rarely happens in the case of famous literary adaptations. All too often, viewers go in expecting an illustration or scene-for-scene realisation of the book – expectations which are either unrealistic or ignore the requirements of the new medium.

For a hugely layered and complex novel, such as Tolstoy’s Anna Karenina, it is totally unreasonable to expect the entire thematic and narrative heft to transfer to screen. To simply dismiss Joe Wright’s (Atonement) adaptation as a vehicle for a shallow love story, or sniffily declare Keira Knightly’s unsuitability for the role is to ignore some very fine filmmaking. Set in and around a theatre stage, the scene changes happen before your eyes and the full architecture of this fantasy theatre is used to the full.

Even the most lenient film critics, though, would struggle to describe Wright’s adaptation as an unequivocal success, lacking as it does in narrative engagement. The visuals often distract from the story, but it is a bold and visually inventive piece of work, deserving of credit for not simply providing an expensive illustration.

Something fitting more firmly into the ‘controversial’ category would be Andrea Arnold’s version of Wuthering Heights. The film had a number of Brontë purists splurting tea into their bonnets at the liberties Arnold took with the story; at one stage having Heathcliff (cast as black) tell the assembled guests of the Earnshaw household to “Fuck off, you cunts.” However, the choices Arnold made in her adaptation are indicative of a provocative filmmaker, who knows which contemporary buttons to press. Her casting of Heathcliff as black, and having a grim kitchen-sink drama feel to the Earnshaw family lends some sort of modern relevance, and breaking free from the stereotypical adaptation. In addition, her realisation of location in Wuthering Heights is simply fantastic, the sound and cinematography bringing the moors and landscape in as a character itself. Far from taking excessive liberties with the story as perceived, she should be applauded for a vision that is both evocative and belligerent, offering something beyond the brand name of a classic novel.

On the reverse of this argument is the upcoming release of On The Road; Walter Salles’ (The Motorcycle Diaries) adaptation of Jack Kerouac’s novel representing the concerns of the postwar Beat Generation. In Salles’ case the feel of Kerouac’s prose and characters have been captured reasonably well, and have been augmented with some fantastic cinematography. However – what is the point? As good as it looks, and as well acted as it is, Salles’ film does not offer anything more than good visuals. It has fallen in to the trap of becoming a slideshow to display along with the book, and that is a failing when it is put to film.

The nature of Kerouac’s prose makes for a disjointed film that lurches unevenly through its narrative. Whilst the novel retains a strangely elegant spontaneity, it does anything but make for an engaging screenplay. Better than most adaptations, then, it shows the desire for cinema to be subservient to the written word is the worst kind of artistic elitism. There is something about lines of text that seems to command greater respect. The idea is that the best prose allows for the imagination to fully realise the characters and worlds of which it speaks – beauty is not in the eye of the beholder, but the mind.

A failure to articulate this on screen is not viewed as an inherent incompatibility with the medium. It is viewed as a failure of the filmmaker’s imagination, or pandering to those who lack the ability to absorb the words into a personal vision. Cinema, however, by its very nature, is a director’s medium, and can transcend the imagination of those observing. The language of cinema is not the language of literature. This is the reason novelisations of films are usually nothing more than pulp garbage.

Although cinema exists in many guises as art, and overall as an art-business duality, lumping the likes of Béla Tarr in with Michael Bay is to ignore this fact. It is about time, especially when certain classic novels have been adapted over and over again, that films were judged on their own terms. Judging them on the basis of how well they represent the book is both an exercise in futility and completely uninteresting. We can expect another version of Great Expectations later this year, from Mike Newell, and Baz Luhrmann takes the reins on a lavish adaptation of F Scott Fitzgerald’s The Great Gatsby. Both have been adapted a number of times, and, as such, it is neither insightful nor helpful to judge the cinematic interpretation on the terms of the written word

Those who hold a misplaced pomposity regarding literature as inherently superior actually flag up an enormous hypocrisy. It could be contested that judging cinema on the terms of a written source is exactly the sort of brand name reductionism that would make the classic authors spin in their graves. It is something the plagues cinema, with remakes of old films judged on the basis of their predecessor rather than what they deliver that is new. Let us not do the same when adapting literature.

The next time you watch a cinematic adaptation, forget prior knowledge and narrative expectations. Take off the reading glasses.