Best Practices in Color Map Selection

The Appeal of the Rainbow Color Map

The rainbow color map spans the entire visible spectrum, from violet to red, and is visually striking. Its appeal lies in its vibrant and diverse range of colors, which can make data visualizations appear more engaging and colorful. However, this aesthetic appeal often comes at the cost of accuracy and clarity....

Problems with the Rainbow Color Map

Non-uniform Perceptual Changes: Rainbow colored map may not provide smooth perceptual modification as the scale of data varies from one end to the other. There can be some inaccuracies in judging the speed of color changes in some frequencies of the spectrum. This might lead to the reluctance of acceptance of the data. For example, those in between yellow and green would seem more obvious than those in between blue and purple when these are representing identical changes. Color Blindness Issues: It is about 0.8% of men’s and 0% of women’s population 5% female population in the whole world has at least some color vision deficiency, which can be the cause of difficulties these women experience in identifying particular colors. The arc of a rainbow, especially because of its largely use of hues, represents a serious issue for people with color vision deficiencies. As a result there may come a time when the viewers do not know what is going on or the message delivered. Misleading Interpretations: The display of such an eye-catching and contrasting color map produces artifacts that are not directly associated with the original dataset. Intermittent color modifications may yield the effect of drastic data switching which may in turn prompt viewers to assume incorrect outcomes. Moreover, the use of vibrant hues in rainbow-themed color scale might distract the viewers and interfere with the main task which is to see the actual data. Poor Grayscale Conversion: When printed in grayscale or viewed by individuals with CVD, the rainbow color map often fails to convey the intended information. This is because the colors do not translate well to shades of gray, resulting in a loss of detail and clarity. Example: A scientific paper that includes a rainbow-colored graph may lose critical information when printed in black and white, making it challenging for readers to interpret the data correctly....

Better Alternatives to the Rainbow Color Map

Perceptually Uniform Color Maps: These three color maps, e.g., Viridis, Inferno, and Plasma demonstrate one important property. Steps in equal data values produce equal in perception changes in color. Viridis is a perceptually uniform color map that transitions smoothly from dark blue to bright yellow. It is designed to be accessible to individuals with CVD and to maintain clarity when converted to grayscale. Viridis is now the default color map in many data visualization libraries, such as Matplotlib.The advantage with these color maps is that they do away with uniformity issues that is common among all rainbow color maps leading to the more accurate data representation. Plasma is another perceptually uniform color map, transitioning from dark purple to bright yellow. It offers a vibrant alternative to Viridis while maintaining the same benefits of perceptual uniformity and accessibility. Cividis is specifically designed for individuals with CVD, offering a color map that is both perceptually uniform and accessible. It transitions from dark blue to yellow, similar to Viridis, but with color choices optimized for those with CVD. Color Blind-Friendly Color Maps: Colormaps like Cividis are designed to be able to be understood by people with a color-vision deficiency as it avoids those spectrums. The maps that are used here are in more or less uniform colors and are very light, so that the visualization can be featured on all types of screens, regardless of whatever type of color blindness that a viewer might have. Sequential and Diverging Color Maps: Color mapping or the representation of a specific data in the form of color is a strong instrument for visualizing various kind of information. Instructions as to different color maps usage will be presented with the purpose to visualize data and pivot numbers within various settings. ‘Blues and Greens’ is an example of a single color map and works best for representing ordered data and ‘Coolwarm’ is a map of unordered data deviating from the central value. These color maps are very useful and have the capacity to explain the situation in an easy-to-understand way and aid to avoid the problems connected with the rainbow color map. As opposed to rainbow color maps which use less colors, they simplify the representation of data and help it to be presented to the viewer more effectively....

Best Practices in Color Map Selection

Consider Data Type:Select a colour map that works along if it is a kind of data to represent (sequential, diverging, or qualitative). For example, examine the range and distribution of data values that need to be studied. Ensure Perceptual Uniformity:First of all, emphasize on color maps that the changes in the color depth are uniform for one pair of colours to prevent misleading interpretation. Evaluate conformance of the implemented color map to the perceptual uniformity principles by means of the respective applications. Test for Accessibility:Check to be sure the chosen color map is not worse than it is for spectrasicobpsians (people with color vision deficiencies) by using color blindness simulators. Make sure that the presentation is understandable and easy to understand from whichever angle of the viewer. Avoid High Contrast and Saturation: Diminish visual artifacts, such as excessive levels of contrast and saturation, by employing color maps with moderate levels of differentiation. Eschew the too vibrant tones that may confuse the audience or shock them....

The Problems with the Rainbow Color Map: Case Studies and Examples

Case Study: Temperature Mapping...

Conclusion

While the rainbow color map may be visually appealing, its non-uniform perception, misleading color transitions, inaccessibility to individuals with CVD, and poor grayscale conversion make it a problematic choice for data visualization. By opting for perceptually uniform color maps like Viridis, Plasma, or Cividis, data visualizers can create more accurate, accessible, and effective representations of their data. These alternatives not only enhance the clarity and interpretability of visualizations but also ensure that the information is accessible to a wider audience, ultimately leading to better communication and understanding of complex data.By understanding the limitations of the rainbow color map and embracing better alternatives, we can improve the quality and inclusivity of data visualizations, making them more effective tools for conveying information in our increasingly data-driven world....