1. One or more computer-readable storage devices with instructions stored thereon that, when executed by one or more processors, perform operations comprising: deriving, from a source image, first appearance content from first spectral data, the first spectral data defined by N spectral channels and including at least one spectral channel outside of a visually perceptible spectrum, the first appearance content being defined by M channels within the visually perceptible spectrum, N being a positive integer value greater than one and M being a positive integer value less than N; mapping the first appearance content to an appearance delta using a gamut mapping algorithm; and deriving, for a destination image, second spectral data from the first spectral data and the appearance delta using a spectral mapping algorithm, the second spectral data defined by K spectral channels and derived to manipulate metamerism to reduce visually perceptible differences in color content when the destination image is rendered and being viewed under varying external illumination conditions, K being a positive integer value greater than M.