Using Reflectance Ratios to Study Animal Coloration

摘要

Reflectance spectrophotometry is used to quantify animal coloration and compare it across individuals, populations or species. While principles of colour perception, pigment-based colour production, and some structural-based colour production, all conform to reflectance differences on a ratio scale, reflectance is usually measured on a linear scale. Processing reflectance spectra on a linear scale distorts colour information (e.g. averaging linear spectra overestimates mean brightness), and computing receiver-independent colour metrics using linear reflectance can bias results (e.g. it underestimates differences in saturation and brightness among dark colours). Working with reflectance spectra on a ratio scale obviates those issues and improves several aspects of colour analysis, from better visualization of reflectance spectra and control of measurement error, to better colour metrics.