Analysing spectral data: comparison and application of two techniques

This study compares two different methods of condensing complex spectral da ta int interpretable indices or metrics of colour. Colour spectra were meas ured on standardized Munsell colour paint chips and estimates of the three fundamental components of colour (brightness, chroma and hue) were generate d using principal component analysis (PCA) and segment classification (SC). We tested the accuracy of these techniques for generating colour component estimates from spectral data in Four different 'colour classes' (red/orang e, yellow/ green, green/blue, and blue/purple) and in an aggregate data set containing all measured spectra. We conclude that both analysis techniques will generally provide more information than more conventional colour asse ssment techniques. Neither technique was superior under all conditions; app ropriateness of each technique depends on the system under study. Efficacy of both techniques depends on the variability present in the data set, grea ter variance in colour tends to reduce overall resolution. An application o f these techniques is also presented in which we characterize sex-specific differences in colour between different populations of the poccilliid fish, Limia perugia. (C) 2000 The Linnean Society of London.