In this spring's adaptation of Alan Moore's seminal comic series, V for Vendetta, Matrix creators, Andy and Larry Wachowski, promise an uncompromising vision of a near-future London dominated by totalitarianism and stalked by a mysterious vigilante. But how much of the original material has had to be compromised to make it suitable for the silver screen? Earlier adaptations of Moore 's comics suggest the task is not easy. Moore has publicly distanced himself from Hollywood on more than one occasion and has expressed a desire to be disassociated from this latest offering as well. In a political climate in which Moore 's original story is still frighteningly relevant, will the Wachowskis' screenplay, in the hands of first time director, James McTeigue, manage to preserve the message or will it be lost in the translation?

Moore built his reputation deconstructing the comic industry's dominant genre, the superhero comic. V for Vendetta, originally published in serial form for Warrior magazine in the 1980s, was one of his earliest attempts to break down the conventions and turn them back on themselves. In an article written for Warrior before the series was complete, Moore described how he and Lloyd resisted the straightforward superhero clich�. Rather than emblazon a giant 'V' Superman-like across the title character's chest, the pair decided on a less conventional costume, dressing him instead as Guy Fawkes.

More significantly, Moore gave moral-ambiguity to his characters. Unlike the mainstream comic heroes and villains of the time, readers were offered characters whose motivations were not black and white. Do we root for the character's fight against totalitarianism despite his terrorist tactics? Perhaps government repression is just ified to bring stability in the aftermath of a catastrophic war? In challenging the moral-absolutism of more popular comic titles, Moore contributed to a shift in the 1980s to a much darker approach to the medium.

By definition, film adaptations must adapt the original material. In the case of science-fiction properties this is particularly so; events in the original comics take place in a near-future that is now recent-past. In 1998, the series maintained, the British would willingly elect a fascist government with a mandate to engage in ethnic cleansing and high-surveillance control to restore order after a third world war. Moore 's story stemmed from his distaste for Thatcherite politics and drew on prevalent fears of nuclear holocaust.

Though the Wachowskis' screenplay retains the bulk of Moore's story, it has clearly been watered-down to find a lucrative market. Audiences familiar with the graphic novel may find the adaptation less challenging. This causes concern because ignoring the complexities of Moore 's work has been a major pit-fall in earlier adaptations. Neither 2001's From Hell nor 2003's The League of Extraordinary Gentlemen drew on those aspects of the comics that made them so fascinating and last year's Constantine, based on a character created by Moore, was similarly deprived. These films demonstrate a reluctance in Hollywood to produce faithful adaptations.

In the graphic novel, From Hell, Moore dramatised a conspiracy theory involving the Victorian serial-killer, Jack the Ripper. More interesting than this, however, was the meandering subtext embroiling ritual, Freemasonry, and Gnosticism in a plot to give birth to the horrors of the 20th century. Because the screen-version touched on these themes only briefly, the end result was an unremarkable murder mystery. In the book, by contrast, the Ripper's identity is known almost from the start. Rather than follow a straight-forward manhunt, the original plot explores the motivations of a serial-killer and suggests a philosophical explanation for the development of modernity. In forcing Moore 's plot to fit a recognisable cinematic structure, much of what set his story apart could not be included.

Stephen Norrington's adaptation of The League of Extraordinary Gentlemen also lacked Moore's distinctive subtlety, this time in the flash of big-name stars and bang of special effects. Moore 's original series, which is rumoured to have been optioned even before the first issue had hit the stands, is a fascinating reinterpretation of the superhero genre. It drew style, characters, and storylines from such 'superheroes' of Victorian literature as Alan Quatermain, Dr Jekyll, Captain Nemo, The Invisible Man and Dracula's Mina Harker. As a team of British secret agents Moore's characters engage with villains from Sax Rohmer's 'Fu Manchu' and H.G. Wells' 'The War of the Worlds'. But while Moore captured the essence of the literature he referenced, the Hollywood version felt superficial and bland. Instead of using the features that stood Moore 's work apart from other comic-book superheroes, the film's creators pigeonholed the original characters into Hollywood stereotypes and introduced new ones to suit the genre. The end result adhered too rigidly to the conventions of the superhero movie.

Most unrecognisable of all, however, was last year's Constantine starring Keanu Reeves in the title role. Many fans of the character, created by Moore in the 1980s, were disappointed by the decision to transform the charming Scouse rogue of the comics into Reeves' dour American cynic. Constantine's new attitude and heritage made the film a more viable box- office success but it meant that once again Moore 's input had been disregarded and his fans reacted accordingly.

So what makes the difference? Why are some comic adaptations vilified by fans and others lauded? The inclusion of the comics' creators in the adaptation process seems to go a long way. The creator of Ghost World, Daniel Clowes, co-wrote the adaptation's screenplay with its director, Terry Zwigoff and fans of the graphic novel declared the adaptation a success. More recently, last summer's Sin City was widely revered by fans of the comic series by Frank Miller. Like The League of Extraordinary Gentlemen, Sin City employed big-name stars and cutting-edge special effects. But the difference between the two films lies in the involvement � or lack thereof � of the original creators. Hollywood had been interested in a film version of Sin City since its debut in 1991, but Miller resisted the lucrative deal until he could be sure his input would be accepted. In fact, he co-directed the film with Robert Rodriguez who left the American Director's Guild rather than follow rules that would have prevented Miller from being credited.

The collaborative nature of comic production has meant Moore has never been able to refuse the rights to his work or demand more input in the adaptation process. He has never been in the same position as Miller who wrote and drew Sin City. No matter how vehemently Moore protests, film-makers have had free-reign when adapting his work.

Following a legal dispute regarding The League of Extraordinary Gentlemen, Moore refused to claim royalties from or have his name associated with any film-adaptation of his work. When V for Vendetta's producer, Joel Silver, claimed Moore was excited about the project, Moore was outraged and demanded the statement be immediately retracted. It was not, so Moore expressed his distaste for the project, allegedly describing the script as "imbecilic". This led many fans to anticipate yet another disappointment.

The concern has always been that V for Vendetta would fall into the same trap as earlier adaptations by ignoring the complex undertones of the original comics. That being said, parts two and three of the Wachowskis' Matrix trilogy demonstrate that the brothers are sometimes prepared to adhere to a film's philosophy even when it draws criticism from fans. In the current political climate, a story about terrorism and repression would be hard pressed to avoid stirring contentious issues and this, of course, was one of Moore 's original intentions. The film's promotional buzz-phrase declares, "People should not be afraid of their governments, governments should be afraid of their people". If cinema-goers draw this message from the film, then fans of the comic should rest assured that its creator's vision has not once again been entirely ignored.