As a user and supporter of accessibility, often times I use a set of specific ColorBrewer color ramps when designing maps.
QGIS has supported ColorBrewer palettes for many years. For more information on QGIS’ ColorBrewer color ramps support, I recommend Anita Graser’s blog posts QGIS Meets ColorBrewer for the step-by-step process and More Color Ramps for QGIS for the updated palettes.
While it’s relatively “easy” to style maps with ArcMap there aren’t any out-of-the-box style solutions incorporating ColorBrewer, leaving the cartographer with two options:
- Customize your colors on-the-fly (good for one time use-cases), or
- Create a customized style file that can be used anytime.
At one time there was a ColorBrewer style file on the no-longer-supported Esri ArcScripts website, but even when the file was accessible the file didn’t meet my needs. Some colleagues found it hard to distinguish the lightest color against lighter-colored backgrounds/basemaps, or when displaying white or gray in a map.
To accommodate the request, I changed the number of data classes in ColorBrewer to one greater than the number I needed. For example: If four data classes were needed in a map, I changed the number of data classes to five and selected the four “darkest” color options:
It wasn’t practical to continually set colors manually in ArcMap, especially when colleagues were doing the same work at their desks. So I needed to create a style file for myself and others. Besides I like getting my hands dirty and finding out the “how” behind why things work. 😛
In order to create my own style, I needed to implement the colors above into my own style. It wasn’t easy; documentation was lacking and outdated. Between software changes and the seemingly less customizations of ArcGIS software, I found myself stumbling through the process. I hope the process below helps other curious cartographers seeking to improve their organization’s workflow.
To create a customized style file I could re-use and share with colleagues I performed the following tasks:
In ArcMap, navigate to the ‘Customize’ menu, and click ‘Style Manager…’:
Once the Style Manager dialog is opened, click the ‘Styles…’ button located in the right side of the dialog box. In the prompt select, ‘Create New Style…’.
A ‘Save As’ dialog will appear, ensure the file is being saved into: C:\Users\<your-username-here>\AppData\Roaming\ESRI\Desktop10.x\ArcMap, and the .style file type is maintained (e.g. ColorBrewer.style). Click ‘OK’ to create the new style.
On the left side of the Style Manager dialog box, a new folder will be created:
There are many ways to create color ramps, as there are four types of color ramps:
- Random: a random alternating band of colors;
- Multi-part: a continuous band of color ramp combinations;
- Preset: an individually-specified color ramp; and
- Algorithmic: a linear stretch between two defined colors.
To create a ColorBrewer color ramp, I used two types of ramps. First, a Multi-part color ramp to combine multiple color ramps together. Then, multiple Algorithmic color ramps to create an algorithm of colors between two defined color values.
There are alternative methodologies to create color ramps, this is the method I preferred. Explore other possibilities while designing your own.
To create the color ramps, navigate to the ‘Color Ramps’ folder > ‘New’ > ‘Multi-part Color Ramp…’:
Next, in the Color Ramp dialog, select the ‘Add’ button > ‘Algorithmic Color Ramp’:
In the Algorithmic Color Ramp select ‘Properties’:
To change the color, select the ‘More Colors…’ button to select a new pre-defined color:
In the Color Selector dialog, switch to “RGB” or “CMYK”, as ColorBrewer lists both.
Change Color 1 to the lightest color and Color 2 to the second lightest color desired. For example: Referencing Figure 1 above, to create the same color scheme, assign Color 1 as (R:178, G:226, B:226) and Color 2 as (R:102, G:194, B:164).
Continue this process using the second lightest color, or Color 2 above, in the “Color 1” value (e.g. R:102, G:194, B:164) and adding in the next darkest value into Color 2 (e.g. R:44, G:162, B:95). Continue until all of the desired colors have been added.
Once completed there will be one less algorithmic color ramp than the number of data classes. For example: With four defined data classes, there will be three algorithmic color ramps.
Continue to add in additional color ramps, and name them along the way (e.g. ColorBrewer Green). Color ramp naming conventions are important as an ArcGIS user can change the display of the color ramps from graphic to textual in the Layer properties symbology by right-clicking the color ramp and unchecking ‘Graphic View’.
Once all of the Color Ramps desired have been added, the style file created can be shared with others by copying the style file to the C:\Users\<your-colleagues-username>\AppData\Roaming\ESRI\Desktop10.x\ArcMap folder.