DEPARDIEU: A BIOGRAPHY By Marianna Gray (Warner, $95) FOR those bored with the smooth image of Hollywood's cardboard cut-out heroes, French actor Gerard Depardieu comes across as a revelation in Marianna Gray's biography. Depardieu is an original, a colourful, unconventional persona with whom the author is clearly enamoured. His story is seen through rose-tinted spectacles from his childhood to his many films and off-screen role as a ''bon vivant''. Both his life and appearance smash the rule books as to what one of the world's leading film stars should be. His nose is almost as bulbous as that of the tragic Cyrano he played in Cyrano de Bergerac. His body is ungainly and overweight and he is normally badly dressed. His hair is ill-kempt and lank. Then there is his past. Ms Gray tells how the son of a heavy-drinking and impoverished sheet-metal worker grew up as a street-fighting, ill-educated youth. He had an ambivalent relationship with the law, and was living with two prostitutes by the age of 16. Finally there is his screen career. Many stars in his position would only deign to appear in movies which enhanced their self-image. But this is a man famous for his lack of selectivity. He gains experience from what he describes in his pidgin English as ''the beeg sheet'', as well as from playing conventional heroes in historical spectacles such as Christopher Columbus in 1492: The Conquest of Paradise. He has done 80 films to date, with roles ranging from a Manhattan cleaner in love with a chimpanzee in Reve de Singe to a homosexual who dresses in drag in Tenue de Soiree. Apart from Depardieu's natural acting talent, the key to his appeal is his voice: the rough reveller who boasts of all-night benders and getting laid is balanced by a man who speaks like a poet, revealing a sensitive, gentle side to his personality. It is this combination of earthiness and poetry that directors have used to such effect in some of France's most successful films, including Jean de Florette and Cyrano . Ms Gray offers some surprising details about the man. One of his closest soul-mates is an actor who would appear to be the antithesis of Depardieu - blue-eyed beauty boy John Travolta of Saturday Night Fever fame. But more than anything, she reveals a man totally involved in the cinema, who has extended his role from actor to producer and distributor. As such he comes across as much more than a star caught up in his own fame but as one of film's few ''real men'' of complex character and diverse talents.