title: Quantifying color variation: Improved formulas for calculating hue with segment classification.
abstract: OBJECTIVE
  Differences in color form a major component of biological variation, and quantifying these differences is the first step to understanding their evolutionary and ecological importance. One common method for measuring color variation is segment classification, which uses three variables (chroma, hue, and brightness) to describe the height and shape of reflectance curves. This study provides new formulas for calculating hue (the variable that describes the "type" of color) to give correct values in all regions of color space. •
  
  
  RESULTS
  Reflectance spectra were obtained from the literature, and chroma, hue, and brightness were computed for each spectrum using the original formulas as well as the new formulas. Only the new formulas result in correct values in the blue-green portion of color space. •
  
  
  CONCLUSIONS
  Use of the new formulas for calculating hue will result in more accurate color quantification for a broad range of biological applications.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado-Boulder, Campus Box 334, Boulder, Colorado 80309 USA.
authors.forename: Stacey D
authors.initials: SD
authors.lastname: Smith
keywords: brightness; chroma; flower color; hue; reflectance spectrum; segment classification