Ross Ihaka Colour for Presentation Graphics ******************************** Choosing a "good" set of colours for a graphical display is an important problem, but one which many data analysis practitioners are ill-equipped to solve. Most current graphics systems provide very little assistance in making good colour choices. Indeed, most systems require that a user specify their colours in ways which are closely related to the hardware representation of the colours rather than to the way we most naturally think about colour. This tends to encourage bad colour choices. In this paper we'll examine some principles and software which enables us to make better colour choices. The ideas are close to those presented by Albert Munsell over 100 years ago, but they will be be developed in a more contemporary framework.