It is obvious where the film companies are hoping to collect the big money this summer, the audience they are trying to attract and what they would like it to be discussing at the start of next term. The “trash” culture of the comic book appeals to teenagers precisely because it is distinct from the culture of school and the adult world, and so faintly subversive. The pleasures of comic-book art are exaggeration, wild fantasy, implausible violence, humour and a taste for the grotesque in all forms. It has always enjoyed a close relationship with the cinema, and computerised special effects now make it possible to realise comic-book fantasies fully on the screen.

Judge Dredd is unusual in being a British creation, with a distinctly ambiguous “hero”. We are nearing the end of the Third Millennium, in an America divided between anarchic Badlands and vast Mega-Cities, where law and order are only maintained by “judges”, appointed to carry out the role of police, court, jury and executioner. Dredd (Sylvester Stallone) is the most effective of all these lawmen, which makes him on one level a typical super-hero, and on another the upholder of an undemocratic and draconian system. “I am the law!”, he declares, on arriving at a trouble spot; “I thought you’d say that!”, as he dismisses the criminal’s defence; and “court adjourned!”, as he puts away his weapon after “justice” has been administered.

The three catchphrases embody the ethos of the film - and the comic, which owed its cult following partly to fans who saw this dystopian vision of the future as a satire on the decaying inner cities of the 1980s, and the policies of governments which had no answer except repression to the decline of communities. The film keeps the irony and visualises a suitably monstrous Mega-City, a combination of high technology and grimy dilapidation, where self-propelled trolleys roam the streets offering “recycled food: it helps the environment and it won’t harm you!” The visual style of all these films is their most significant feature. When on duty, all the heroes (Dredd, Batman and the Power Rangers) wear helmets that mask most of their faces, particularly the eyes, and uniforms that express the essence of the creatures inside. Dredd is kitted out like a robot, with cumbersome boots, metal breastplate and shiny epaulettes: he is, after all, a close cousin of RoboCop, and meant to move with the implacable persistence of a remote-controlled machine. Batman, on the other hand, has a black leather outfit more in keeping with the camp humour of the film. The Power Rangers dress in lighter and brighter costumes, like angelic bikers, which allow them to perform their balletic stunts while leaving no doubt that they are clean-living, clean-minded teenagers when off duty; their opponents are grotesque, insect-like, or inhumanly metallic. There is none of the moral ambivalence of Dredd or the sexual ambivalence of Batman in the Rangers.

The inner lives of all the heroes are, by contrast, very plain. The Power Rangers are devoid of personality. Batman is driven by a desire for justice which comes from having been psychologically damaged as a child when he saw his parents murdered in front of him. This is a common childhood experience for heroes in all ages; it was also used to explain what drove Sir Lancelot, in First Knight. Nothing like that can account for the behaviour of Judge Dredd, however. He was cloned from a cocktail of selected genetic material, but doesn’t look much as if he would be upset by a broken test-tube. Anyway, normal human emotions are a problem for most super-heroes.

Batman Forever, like the two earlier Batmen directed by Tim Burton, is set in a Gotham City which represents a kind of future-in-the-past: sci-fi technology against a background of 1930s baroque. The director this time is Joel Schumacher. Most of the outdoor action takes place at night and it is easy to see the facial masks and the camp playacting as figures for concealment of identity, particularly sexual identity. Batman (Val Kilmer) is allowed to fall in love (with Nicole Kidman), while coyly evading the advances of Robin (Chris O’Donnell), who would like to become his assistant. His main enemy is a grotesquely mutilated former District Attorney - called Two-Face.

There are no such depths in Mighty Morphin Power Rangers, which is straightforward science fiction, with a hint of Zen, grafted on to a contemporary setting. The target audience is correspondingly younger, and likely to identify, not with the almost featureless heroes themselves, but with the pre-teenage boy who hovers admiringly around them. You, too, may be a Power Ranger in time, he is told - “nothing is impossible”. No, not at that age, particularly with a large budget and a powerful computer. All three pictures offer entertainment for young people at different stages of adolescence, loud, vivid, superficially violent, short on psychology and ideas. The only risk is that a few cultists, impressionable kids or teachers of media studies may be tempted to take them too seriously.