Beyond the Rainbow: Effective Color Palettes for Nature Journals
Why the classic rainbow colormap distorts data, and how to choose perceptually uniform palettes that are accessible to colorblind readers.
For decades, the rainbow (or Jet) colormap was the default for visualizing heatmaps and scientific data. Recent studies have highlighted substantial flaws in this approach. The transition from red to blue introduces artificial banding that can mislead the eye into seeing boundaries where none exist.
The Problem with Jet
The human eye does not perceive changes in color magnitude linearly across the rainbow spectrum. Yellow often appears brighter than red or blue, creating false peaks in data visualization. This is not just an aesthetic issue; it is a scientific accuracy issue.
Designing for Accessibility
Approximately 8% of men and 0.5% of women have some form of color vision deficiency. When red and green are the only contrast, that data can become invisible to a significant portion of the scientific community.
import matplotlib.pyplot as plt
import numpy as np
data = np.random.rand(10, 10)
plt.imshow(data, cmap='viridis')
plt.colorbar()
plt.show()
Recommended Palettes
We recommend switching to perceptually uniform colormaps. These are designed so that equal steps in data value correspond to equal perceptual steps in color.
- Viridis: Excellent for sequential data. Dark purple to yellow.
- Magma: High contrast, black to white-pink. Good for printing in grayscale.
- Cividis: Specifically optimized for color vision deficiency.
Tools and Resources
Before submitting your next paper, check your figures using tools like Color Oracle or Adobe Illustrator's Proof Colors view. Small changes in your color workflow can improve the impact of your research.
Frequently asked questions
- Why avoid rainbow (Jet) colormaps in papers?
- Jet creates false banding and uneven brightness, which can invent structure that is not in the data and confuse reviewers.
- Which colormap should I use for heatmaps?
- Prefer perceptually uniform maps such as Viridis, Magma, or Cividis. Cividis is especially strong for color-vision deficiency.
- How do I check figures for colorblind accessibility?
- Use Color Oracle, Adobe Illustrator Proof Colors, or CVD simulation plugins before submission.
More guides on the Sciicons blog · Browse scientific illustrations · Free figure tools