Title: colorspace: A Toolbox for Manipulating and Assessing Color Palettes for
Statistical Graphics

Authors: Achim Zeileis, Jason C. Fisher, Kurt Hornik, Ross Ihaka, Claire D.
McWhite, Paul Murrell, Reto Stauffer, Claus O. Wilke

Affiliation: Universität Innsbruck

Abstract:
The R package "colorspace" provides a broad toolbox for selecting individual
colors or color palettes, manipulating these colors, and employing them in
various kinds of statistical graphics
(http://colorspace.R-Forge.R-project.org/). In particular, the package
provides a broad range of color palettes for different kinds of displays based
on the HCL (hue-chroma-luminance) color space. The three dimensions of the HCL
space have been shown in psychophysical experiments to match those of the
human visual system very well, thus facilitating the selection of color
palettes through trajectories in this space.

Namely, general strategies for obtaining the following three types of palettes
are provided: (1) Qualitative for coding categorical information, i.e., where
no particular ordering of categories is available and every color should
receive the same perceptual weight. (2) Sequential for coding ordered/numeric
information, i.e., going from high to low (or vice versa). (3) Diverging for
coding ordered/numeric information around a central neutral value, i.e., where
colors diverge from neutral to two extremes.

To aid selection and application of these palettes the package provides scales
for use with ggplot2; shiny (and tcltk) apps for interactive exploration (also
online at http://hclwizard.org/); visualizations of palette properties;
accompanying manipulation utilities (like desaturation, lighten/darken, and
emulation of color vision deficiencies).