Graphics Reference
In-Depth Information
forms of color blindness. Using Vischeck for red-green color blindness with
the previously shown diverging color scales results in what is shown
Figure
5-11
.
Using pure red and pure green for diverging color is usually considered
ineffective for the color blind—the red-green diverging colors in the figure
have blue mixed with the green to create some difference. Note how the
blue-orange palette appears to have more differentiation.
Figure 5-11:
Two color scales. The upper image shows the original color
scale, and the lower image shows the color scale after simulating red-green
color blindness (using
vischeck.com
).
Note
Numerous websites exist that can generate good colors. ColorBrewer
(
colorbrewer.org
) is a well-known resource for creating effective color
palettes of all three examples. You can also use a color recommender
(
http://aperturejs.com/colorrecommender/index.html
)
to generate
palettes.
Labels
Labels can be one of the most important enhancements to a graph. Labels
unambiguously identify specific nodes (or links). The topology may reveal
that there is a critical node connecting two clusters, and the color may
indicate importance, but a label is required to reveal the specific identity
of the node. Interactions such as tooltips or selection (discussed in Chapter
6, “Explore and Explain”) can reveal node identity, but it is important to
remember that those interactions are lost once the graph is shown as an
image in a PowerPoint presentation, a printout, or a PDF file.
