1. A method comprising: at a computer, converting coordinates of source reference points in a color space to coordinates of destination reference points in the color space; and at the computer, converting coordinates of an initial point to coordinates of a target point based on a first relationship among a first set of volumes and a second relationship among a second set of volumes, the initial point being different from the source reference points, the target point being different from the destination reference points, the first set of volumes being defined at least in part by the initial point and at least a subset of the source reference points, the second set of volumes being defined at least in part by the target point and at least a subset of the destination reference points.