Simply Scattered: Enhancing Color With Geometry in a Visualization
By: Theresa-Marie Rhyne
Tags: Charts, Data Visualization, Color Theory, Graph, Design

Simply Scattered: Enhancing Color With Geometry in a Visualization

How to survive color deficiencies in line and scatter plots

In my previous “Colorizing a Visualization” writing, I covered the analogous and complementary color harmonies. Today, I will discuss a hybrid of the two harmonies called the Analogous Complementary Color Harmony. This is also called an accented analogous color harmony.

In this example, the online Adobe Color tool facilitates the building of this harmony in the key of Blue. The resulting Accentuated Blue harmony is applied to a scatter plot with a line visualization that fails color deficiency tests.

Analogous as well as Analogous Complementary Color Harmonies run the risk of failing color deficiency tests since the resulting color themes include multiple colors next to or adjacent to each other on the Color Wheel. This increases the difficulty in distinguishing between color elements in a visualization for normal color vision as well as color deficient individuals.

In this writing, an approach to salvaging a visualization that fails a color deficiency test is shown. This situation is likely to happen to you in your practice of visualization. This issue is addressed by using a different geometric element or shape for each data set in addition to the Accentuated Blue color scheme. The differences in color are enhanced using Geometry based changes to overcome the failing color deficiency tests. That is to say, encoding categories using shape or size.

Fundamentals of an Analogous Complementary Color Harmony

In visualizing quantitative information, there is frequently a need to include the average, median, historical context or other trends in multiple data sets. The trend is frequently distinguished from the other data elements. An Analogous Complementary or Accented Analogous Color Harmony is an effective color theme for achieving this. This Color Harmony includes one Complementary color opposing a set of colors all in the same Analogous family. The trend data can be colorized in the Complementary hue with the remaining data sets colorized with the Analogous hues. To visually understand the fundamentals of the Analogous Complementary Color Harmony, I depict an Analogous Color Harmony and the Complementary Color Harmony separately below.

The Analogous Color Harmony refers to colors that are adjacent or next to each other on the Color Wheel. While the Complementary Color Harmony represents colors that oppose or are across from each other on the Color Wheel. Using Adobe Color, a web-based app for creating color themes, I depict both in the Key of Blue: #121EFF.

Analogous and Complementary Color Harmonies in the Adobe Color Tool.

The Analogous Color Theme consists of a Cyan #0595FF, three Blues (#054CE8, #121EFF, #3705EB), and Purple #8005FF as shown on the left.

While the Complementary Color Theme consists of three Blues (#121EFF, #2B36FF, #060FB3) and two Yellows (#B38F00, #FFCF12). The Yellow #FFCF12 represents the pure complement to Blue #121EFF.

The Red-Green-Blue (RGB) Color Wheel is used in these examples and is based on the concept that R, G, and B are the color primaries for viewing displays like what we see on our desktop and mobile devices.

Creating the Analogous Complementary Color Harmony

Since Adobe Color does not provide a specific Analogous Complementary Color Harmony, the next steps involve building this color theme.

Step 1: Moving from Analogous to Custom Harmonies in Adobe Color to create the Accentuate Blue Color Theme.

Starting with the Analogous Color Harmony for the Key of Blue #121EFF, Step 1 is to transition from an Analogous Harmony option to a Custom Harmony in Adobe Color.

Step 2: Moving Blue #054CEB to the center of the Color Wheel to produce White #FFFFFF.

Step 2 is to move the second Blue #054CEB on the left to the center of the Color Wheel to produce a neutral White #FFFFF.

Step 3: Moving Blue #3705E8 to the Yellow #FFCF12 pure complementary color.

Step 3 is to move the second Blue #3705E8 from the right to correspond to the Yellow #FFCF12 pure complementary color. This yields the Analogous Complementary Harmony in Adobe Color.

Color Wheel for the Analogous Complementary or Accentuated Blue Color Harmony.

To summarize our results, an enlarged Color Wheel of the Analogous Complementary or the “Accentuated Blue” Harmony is shown to the left.

There are three analogous colors of Cyan #0595FF, Blue #121EFF and Purple #8005FF with a complementary Yellow #FFCF12. Each of these colors will be used in a Scatter Plot with a Line visualization below.

Applying Accentuated Blue to a Scatter Plot Visualization

Now, let’s apply the “Accentuated Blue” theme to our chart. In this example, I do not label the X or Y axes as would be done in a formal visualization. My efforts here are to focus on the color and shape elements of the composition.

Accentuated Blue Color Theme applied to a Scatter Plot with Line Visualization.

Here, the Scatter Plot with Line example is used where data points from the three data sets are plotted as equal sized circles. Each data set is assigned an individual color of Cyan #0595FF, Blue #121EFF, and Purple #8005FF, respectively. A straight Yellow #FFCF12 line superimposes the Scatter Plot and represents the average of all three data sets. You may notice that the Blue #121EFF circle is occluded by the Cyan #0595FF circle at step 12 on the X axis.

Software tools such as Microsoft Excel or Word, Apple Numbers or Pages, Google Docs, Tableau Software and many others can help generate this example.

Evaluating the Scatter Plot for Color Deficiencies

In humans, there are three types of photoreceptors or cones where each is sensitive to different parts of the visual spectrum of light to facilitate rich color vision. If one or more of the set of cones does not perform properly, a color deficiency results. A Red cone deficiency is classified as protanopia. A Green cone deficiency is classified as deuteranopia. A Blue cone deficiency is classified as tritanopia.

For the Scatter Plot with Line visualization here, I use the online Color Blindness Simulator, Coblis, to check for color deficiencies. These results are shown below.