Rainbow Colormap


#1

Guideline: Rainbow color Map is considered harmful
Source: D Borland and M T Russell II, Rainbow Color Map (Still) Considered Harmful, CG&A, 27(2), 2007.

Question:
I represent a group of environmental scientists. We see and create visualizations with rainbow colormaps in thousands. It would be a pain if everyone uses a different colormap for each variable in these visualization. Is there a standard colormap we can use as a default map that everyone understand? Can visualization researchers be more constructive by recommending a colormap that maximize the perceptual bandwidth while minimize the problems such as being unsuitable for color blindness?


#2

Perhaps the work Matplotlib colormaps might be of interest to you and your colleagues:

https://bids.github.io/colormap/

In short the “Jet” colormap (that can also be called a rainbow color map) was a default in Matplotlib for many years. In 2015/2016, it was replaced as the default colormap by a blue to green to yellow colormap entitled “viridis” : https://bids.github.io/colormap/images/screenshots/option_d.png

There is still much research underway in the IEEE VIS community in regard to understanding the appropriate use of the Rainbow Color Map for visualization purposes. As you have wisely noted, it is a challenge to maximize perceptual bandwidth and support color deficiencies.

Awhile back, in November 2016, I wrote a book on “Applying Color Theory to Digital Media and Visualization” - published by CRC Press:

The book grew out of some of my experiences in creating visualizations at and for the United States Environmental Protection Agency as well as other work at other institutions like North Carolina State University.

I also went back and read some of Newton’s writings in his famous book entitled “Optics: or, a Treatise of the Reflexions, Refractions, Inflexions, and Colours of Light” published in 1704. Newton was very precise in his diagrams of his optics experiments. These diagrams include precise placement of the locations of the color values of Red, Orange, Yellow, Green, Blue, Indigo and Violet that formed his original rainbow color map and his color circle (that is now often called a color wheel). Over the centuries, we have reinterpreted Newton’s original work in many scientific and artistic endeavors.

As humans, we can be prone to making mistakes in our judgements when it comes to viewing and understanding a given visualization no matter what color map is used. If the decision is that critical, and sometimes it might be, my recommendation has always been to look at the data using a varied set of visualization methods and color maps. After having created many visualizations for a long period of time, I have to humbly say that no one color map or visualization works for every situation. To me, that is the mystery and unexpected wonder in practicing visualization.

My hope is that this response might be helpful to you.

Theresa-Marie Rhyne