Willingly or not Derek Jarman has been part of a loose tradition among British film-makers (Greenaway, Ridley, etc.) who do not restrict themselves to the one medium, but demonstrate a disposition towards investigating further the component parts of that particular process through writing and, most tellingly, painting. Consequently, in addition to his films, Jarman has been an enthusiastic and widely exhibited artist, ranging from his cool, precise theatrical designs and landscapes to the collage work and huge canvasses shrouded in tabloid headlines or brain-scan images, smeared in thick, angry colour. Chroma is therefore something of a natural extension.

Subtitled 'A Book of Colour', it was birthed, according to its author, as an antidote to the dry, academic texts on colour forced upon art students - a literal celebration and exploration of colour in all its forms. The resulting work runs from White (WHITE LIES) to Black (BLACK ARTS), backed with additional chapters on Silver and Gold, Iridescence, and - most fascinatingly - the Translucence of glass: "It was through an 'absence' of colour - colourlessness - that we measured the stars, created the spectrum. Then came the microscopes to reveal the invisible within."

Jarman's method is at once simple and surprisingly illuminating, a lyrical combination of personal anecdotes and thoughts, and quotes from the likes of da Vinci, Newton, Ginsberg and Wittgenstein. From a purely practical bent the author might explain the evolution of painters' reds - VERMILLION, ALIZARIN CRIMSON ("It's one of the most stable of natural dyestuffs"), RED LEAD, VENETIAN RED ("Used as a warm ground in Venetian painting"), CADMIUM RED - or the history of Orange: "Orange is a newcomer. Cadmium and chrome orange were discovered in the early nineteenth century." But more often than not the texts are linked with streams of consciousness, free associations of colour: "In the first white light of dawn I turn white as a sheet, as I swallow the white pills to keep me alive...attacking the virus which is destroying my white blood cells."

Greatly written in hospital in June 1993, the book inevitably takes on the autobiographical tone of much of his published work, reminiscences of his parents, visits to Greece and Italy, or reflections upon his films. And inevitably Chroma is suffused with the AIDS infection slowly killing its author, operating as something of a companion piece to one of his last films, Blue. Indeed, that chapter (INTO THE BLUE) is taken from the film's script - the collapse of his eyesight ("If I lose half my sight will my vision be halved?"); the deaths of friends; the grind of medication and hospital. "I place a delphinium, Blue, upon your grave."

As an academic text on colour Chroma may be found wanting, and outside the wide circle of Jarman's admirers this slim but tidy collection of the scholarly and personal might be found far too introspective and subjective to stomach. But for those who care, this is a charming, angry and compassionate addition to the already bulging library of one of our most celebrated and honest visual artists.