Updates to ColorBrewer Resources

Hello ColorBrewer user. I have been getting good feedback from users from all over, and I am glad this web tool is helping you make better maps. 

I have offprints from a journal article with a full set of printed schemes with CMYK specs that I can mail out to you (item 1. below). You can download an Excel file of RGB specs for the full set of schemes (2.). I also added notes below on citation (5.) and a related book and course (6.).

1. CMYK specs
A full set of CMYK color charts for ColorBrewer schemes are printed in CaGIS and I have offprints that I will send out to you (free). I admit to being slow responding to these requests so pester me if I don't get back to you. Here is the article reference:
    Brewer, Cynthia A., Geoffrey W. Hatchard and Mark A. Harrower, 2003, ColorBrewer in Print: A Catalog of Color Schemes for Maps, Cartography and Geographic Information Science 30(1): 5-32.

The color charts are reprinted as an Appendix in my book Designing Better Maps: A Guide for GIS UsersThis version of the charts has both CMYK and RGB specs next to each color patch.

These color charts will assist ColorBrewer users whose color maps are professionally printed using an offset lithographic press. Geoff Hatchard and I imageset negatives, proofed, and adjusted the ColorBrewer schemes to prepare this article in the summer of 2002. We improved the CMYK specs for about 80 colors and adjusted all of the corresponding numbers (RGB, Lab, Hex, and AV3). The costs of the negatives, proofs, and Geoff's time were funded by our NSF Digital Government grant through GeoVISTA.

Two other articles are also out (but no color charts are in these ones):
    Brewer, Cynthia A., 2003, A Transition in Improving Maps: The ColorBrewer Example, in U.S. Report to the International Cartographic Association, special issue of Cartography and Geographic Information Science 30(2):155-158.
    Mark A. Harrower and Cynthia A. Brewer, 2003, ColorBrewer.org: An Online Tool for Selecting Color Schemes for Maps, The Cartographic Journal 40(1): 27-37.

2. RGB file
I have had some requests for these color schemes in alternative formats from people who want to build the schemes into their own programs or capture them more efficiently. I have linked Excel files with all of the ColorBrewer RGB numbers for each color in each scheme at each number of classes (1690 lines).

There are two RGB files on this page. One is bare-bones with schemes in alphabetical order. In the second file the schemes are in the same order as they appear in ColorBrewer and RGB color patches are embedded as comments in each row. Thank you to David P. Ryan for initiating this upgrade to the file and doing the Excel programming to insert the color patches.

In return for using these specs, I would like you to lavishly credit the source of the color schemes (see item 5. below). 

Also, please take a moment to email me a short note on how you will use the color sets <cbrewer@psu.edu>. That helps me make the case of applicability of my work for University merit evaluations. I also enjoy news about how this design work is useful in varied applications.

3. Colorblind
In addition to my rough guidance on suitability of schemes for colorblind readers, you can do a better job of preparing map colors for colorblind map readers using the tools at  www.vischeck.com. Capture and submit your map legend as a small graphics file and see what changes their 'Daltonize' function suggests. I learned about this tool in a newsletter article by Jeff Nugent (p. 6).

If you know of other colorblind utilities on the web for diagnosing or adjusting graphics, please email me with a tip. This is a topic I have previously done research on and I am interested in progress on new tools. The research behind Vischeck is sound so I suspect this tool is giving pretty good results, though the details of the translation to RGB on your particular computer screen will potentially diminish the results. Thanks.

Steve Gardner's Master's thesis evaluated the ColorBrewer schemes for colorblind readers. I've linked his whole thesis with his permission (6.1MB .PDF file or 5.5MB zipped which isn't smaller but it may download more smoothly). He has recommendations that I have not yet incorporated into the schemes, so I want to get that info out to you. Please cite his work if you find it useful. Also, I hope his work prompts further student research. Steve is now working at the National Geographic Society. 

4. Copyright
I have adopted an 'Apache license' for ColorBrewer and its color schemes, on the initial advice of Frank Hardisty. Alan Isaac recommended updating to Version 2.0 for compatiblity with GPL licenses. Thanks Frank and Alan.
Here is the license:
Apache-Style Software License for ColorBrewer software and ColorBrewer Color Schemes

Copyright (c) 2002 Cynthia Brewer, Mark Harrower, and The Pennsylvania State University.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
You may obtain a copy of the License at


Unless required by applicable law or agreed to in writing, software distributed
under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied. See the License for the
specific language governing permissions and limitations under the License.

This text from my earlier Apache License Version 1.1 also remains in place for guidance on attribution and permissions:

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
1. Redistributions as source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. The end-user documentation included with the redistribution, if any, must include the following acknowledgment:
"This product includes color specifications and designs developed by Cynthia Brewer (http://colorbrewer.org/)."
Alternately, this acknowledgment may appear in the software itself, if and wherever such third-party acknowledgments normally appear.
4. The name "ColorBrewer" must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact Cynthia Brewer at cbrewer@psu.edu.
5. Products derived from this software may not be called "ColorBrewer", nor may "ColorBrewer" appear in their name, without prior written permission of Cynthia Brewer.

5. Citation
Ahhh, that lavish citation I'm hoping for...
Wording depends on context and I'm not too picky. If you add a note in the corner of a map, how about one of these:
    - Colors from www.ColorBrewer.org by Cynthia A. Brewer, Geography, Pennsylvania State University.
    - Map colors based on www.ColorBrewer.org, by Cynthia A. Brewer, Penn State.
    - Color symbols: ColorBrewer.org
A reference in a journal article or report might look like:
    - Brewer, Cynthia A., 200x. http://www.ColorBrewer.org, accessed date.

6. Learning Map Design
And if you are looking for more advice on mapping, take a look at my map design handbook:
      Designing Better Maps: A Guide for GIS Users, 2005, ESRI Press, ISBN 1589480899.
Here's the Amazon link and another link to summary chapter titles and section headings.
I'd like to acknowledge my editors, Judy Hawkins and Edie Punt, at the press and great book layout work by Jen Galloway.

My Cartographic Design course has also been re-launched, updated for ArcGIS 9.0, on the ESRI Virtual Campus. Thank you to Suzanne Boden for the update work.

7. Color Ramps in ArcMap 
A variety of people have talked to me about the tedium of typing in numbers and wanting schemes with more classes. I do think you'll need to set the color numbers for each legend patch to get the best schemes, but here a few tips for ArcMap users.

For ramping from the Symbology tab, type in specs for the end points and one or two intervening colors from a set of seven or so colors from a ColorBrewer scheme. Select the middle color(s) you specified and hold the control key while you ramp. That will approximate the ColorBrewer scheme without having to type them all in. ColorBrewer colors are each individually designed (I didn't make them by ramping) so the result will only be approximate. Using many more colors in a ramp than I offer will give you an overall form for the distribution you are mapping but not differentiable or identifiable color classes.

Also, if you have typed in a set of colors that you use often, get to know the Style Manager function (Tools menu->Styles->Style Manager). You can save each color in a .style file and then have those available on the left side of your Symbol Selector window for your other projects (check your style file name in the list opened with the More Symbols button). You can also share these .style files in your work group. I haven't prepared all these .style files, but I'd be happy to post them on my web site, or list links here, if some of you have already prepared them and would like to share.

These tips are for ArcMap 8.x up to 9.1.

8. More Brewers?
I've had some conversations with colleagues about expanding the idea of ColorBrewer to assist mapmakers with other design challenges. Though extending this somewhat silly naming to other areas makes me squirm, other researchers seem keen. I'm happy to contribute my name to a proliferation of good design advice. Ben Sheesley is contemplating creating a Type Brewer for his PhD work, advised by Mark Harrower, and Olaf Schnabel is working on a Symbol Brewer for his PhD.

In the cartographic context, I think a “brewer” has eight characteristics:
1.  A selection of choices are offered for a specific representation challenge (a brewer is not simply a general lesson in principles).
2.  Choices are organized by a set of mapping principles made explicit to the user (the choices are not merely listed in an unstructured catalog).
3.  All of the choices offered are potentially suitable for problems for which the tool is used (there are no extreme choices or straw men in a symbol set).
4.  All choices can be examined as categories are explored, encouraging the user to learn about criteria for applying the existing variety of choices.
5. Choices are not software specific (solutions can be implemented in multiple mapping applications).
6. Only basic skills in the use of mapping software are needed to implement the representations offered (programming skills are not required).
7.  Representations are further augmented with tips on their suitability, though the user making a quick selection can ignore these details.
8.  Users are encouraged to be critical of the choices offered, evaluating them with a display that will reveal potential shortcomings.

These eight points are from the short paper I contributed to the 2003 U.S. National Report to the International Cartographic Association. The paper is titled "A Transition in Improving Maps: The ColorBrewer Example" [Cartography and Geographic Information Science 30(2):155-158].

The photo below shows Olaf (left), Mark (right) and I clowning around at the ICC2005 meeting in Spain. You can't you tell what we are doing?...that's S, C, and T for Symbol-, Color-, and Type-Brewer.

Olaf, Cindy, Mark at ICC2005

My collaborator and master Flash programmer, Mark Harrower, is an Assistant Professor of Geography at the University of Wisconsin--Madison. Steven Gardner, Jess Dobrowolski, and Anthony Scardino have helped me improve the icon settings for colorblind and media suitability (lower left). 

The final URL for ColorBrewer is a fairly long link to my personal web space at Penn State. You can direct colleagues to the shorter URL http://colorbrewer.org (since it's easier to remember) and it will forward them to the actual location of the program. I'd like to thank Dennis McClendon for taking the lead on creating that nicely-shortened forwarding URL.

A summary collection of all of the ' learn more ' information from seven buttons, plus icon descriptions, in the ColorBrewer interface is linked. Basic instructions on using ColorBrewer are also available online.

Cindy Brewer , July 2006