Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2020 Oct 28;11(1):5444.
doi: 10.1038/s41467-020-19160-7.

The misuse of colour in science communication

Fabio Crameri  1 , Grace E Shephard  2 , Philip J Heron  3
Affiliations
Review

The misuse of colour in science communication

Fabio Crameri et al. Nat Commun. .

Abstract

The accurate representation of data is essential in science communication. However, colour maps that visually distort data through uneven colour gradients or are unreadable to those with colour-vision deficiency remain prevalent in science. These include, but are not limited to, rainbow-like and red-green colour maps. Here, we present a simple guide for the scientific use of colour. We show how scientifically derived colour maps report true data variations, reduce complexity, and are accessible for people with colour-vision deficiencies. We highlight ways for the scientific community to identify and prevent the misuse of colour in science, and call for a proactive step away from colour misuse among the community, publishers, and the press.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. The superiority of scientifically derived colour maps.
By knowing what something looks like in advance, the distortion by unscientific colour maps, like jet or rainbow, becomes instantly obvious. The look of scientific data is, however, usually unknown a priori, which makes the distortion of an unscientific colour map, and the true data representation of a scientifically derived colour map, like batlow, less apparent. Marie Skłodowska-Curie, as originally photographed by Henri Manuel around 1920, the Earth from space, and an apple are shown a in their original images and b in distorted and c in undistorted colour versions. Inferring the true picture from an unscientifically (e.g., jet) coloured data set is incomparably harder than from a data set represented in a perceptually uniform and ordered colour map, like batlow.
Fig. 2
Fig. 2. Colour vision tests.
Available perceptually uniform colour maps versus the non-uniform rainbow (i.e., jet; bottom row) as seen with either of the three common forms of human colour-vision deficiency (deuteranopia, protanopia, and tritanopia), and for grey-scale (representing total colour-blindness or simple black-and-white prints). Rainbow, the most-widely used colour map, fails to reproduce a meaningful smooth gradient, yet the other colour maps (see Box 2) are all universally readable.
Fig. 3
Fig. 3. Colour map measure, distortion, and error.
a, b The incremental lightness difference, ΔE, here using the CIEDE2000 formulation (see ‘Methods’), is a measure for the perceptual colour difference along the colour map. For a perceptually uniform colour map, ΔECIEDE2000 should be equal all along the colour map (i.e., a flat graph; a). Using c, d the cumulative colour lightness difference, ΔECumulative, it is possible to extract e, f the resulting visual error in percentage of total data variation. For scientifically derived colour maps like batlow, the resulting error introduced to the data by the colouring is negligibly small as g the incremental data variation is represented equally all along the axis, and a linear data gradient, therefore, appears linear. Put differently, i a flat line looks flat. For non-scientific colour maps, like jet, h data gradients are unevenly represented and f visual error can be >7% of the displayed data variation such that j a linear graph (e.g., a flat line), for example, becomes unrecognisable.
Fig. 4
Fig. 4. Perceptual uniformity and order.
A constant incremental colour and lightness contrast along a colour map is a proxy for its perceptual uniformity. a While a certain incremental data variation is either under- or strongly overrepresented with jet (a.k.a. rainbow) depending on the colour map segment, it is instead b evenly represented all along a colour bar when using a scientific colour map like batlow, due to its uniform colour and lightness contrast. Perceptual order is given when individual colours of a colour map can be sequentially ordered effortlessly without consulting the colour bar. While c a sequential ordering is not intuitively possible for jet (a.k.a. rainbow), it is d possible to sequentially order individual colours of a scientifically derived colour map like batlow, thanks to its constant lightness gradient.
Fig. 5
Fig. 5. Colour map classes and types.
The various classes of colour maps (sequential; diverging; multi-sequential; cyclic) and types (continuous; discrete; categorical). Only sequential colour maps can be faithfully applied to categorical types of data.
Fig. 6
Fig. 6. Guideline for choosing the right scientific colour map.
For effective data representation, the nature of a given data set has to be matched by a suitable colour map class, type, and colour combination.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Akiyama K, et al. First M87 event horizon telescope results. IV. Imaging the central supermassive black hole. Astrophys. J. Lett. 2019;875:L4. doi: 10.3847/2041-8213/ab0e85. - DOI
    1. Long, E. Election Data Visualisation (University of Plymouth, 2013).
    1. Cox, A., Bostock, M., Watkins, D. & Shan, C. The Most Detailed Maps You’ll See from the Midterm Elections., https://www.nytimes.com/interactive/2014/11/04/upshot/senate-maps.html (2014).
    1. Lemoine FG, et al. An improved solution of the gravity field of Mars (GMM-2B) from Mars Global Surveyor. J. Geophys. Res.: Planets. 2001;106:23359–23376. doi: 10.1029/2000JE001426. - DOI
    1. Hawkins E. Scrap rainbow colour scales. Nature. 2015;519:291 EP. doi: 10.1038/519291d. - DOI - PubMed

Publication types