This story is part of a series on bringing the journalism we produce to as many people as possible, regardless of language, access to technology, or physical capability. Find the series introduction, as well as a list of published stories here.

I am one of the 8% of men of Northern European descent who suffers from red-green colorblindness. Specifically, I have a mild case of protanopia (also called protanomaly), which means that my eyes lack a sufficient number of retinal cones to accurately see red wavelengths. To me some purples appear closer to blue; some oranges and light greens appear closer to yellow; dark greens and brown are sometimes indistinguishable.

Sim Daltonism lets you visualize colors as they are perceived with various types of color blindness. Move the Sim Daltonism window over something on the screen and see what it looks like with a color blindness. The best alternative is Sim Daltonism, which is both free and Open Source. The list of alternatives was last updated Apr 17, 2017 Color Oracle info, screenshots & reviews Alternatives to Color Oracle.

Most of the time this has little impact on my day-to-day life, but as a news consumer and designer I often find myself struggling to read certain visualizations because my eyes just can’t distinguish the color scheme. (If you're not colorblind and are interested in experiencing it, check out Dan Kaminsky’s iPhone app DanKam which uses augmented reality to let you experience the world through different color visions.)

As information architects, data visualizers and web designers, we need to make our work accessible to as many people as possible, which includes people with colorblindness.

Color is critical

Color is frequently used to quickly convey meaning. It's an important choice for any visualization, but making one that's attractive, informative and easily distinguishable by colorblind people trips up many designers.

The NPR Visuals team worked through these challenges this spring in a visualization for a story on how school districts spend money.

“Early on after some doing some exploration of the data we knew we were going to do a district level choropleth map,” said Katie Park, deputy graphics editor at NPR. “We thought that it would be easier to read with a diverging color palette where the center value was the U.S. average. When you get into divergent color palettes you realize that colorblindness might become an issue.”

Park said that the default color schemes designers might use — like green for positive values and red for negative values — tend to cause problems for colorblind readers.

Meanwhile, common colorblind friendly palettes like magenta/green or orange/purple are devoid of meaning. Pink, for example, doesn’t convey negativity like red does. Others, like blue/red, are already imbued with too much cultural meaning and would be confusing in a non-political map.

Sometimes you can get away with using a single hue and varying its lightness. But sometimes a project calls for a multi-hue scale or a diverging scale. (If you’re interested in reading more, The New York Times’ Gregor Aisch wrote a blog post about his library chroma.js that goes into more detail on multi-hue scales)

Three tools to help

There are a few simple tools to help ensure that your projects are colorblind-friendly.

1. Start by using the color schemes on ColorBrewer, which gives you sequential, diverging, and categorical (sometimes called binary) palettes that are colorblind safe. You can use these and modify them to fit your style guide. “I try to find a good compromise between our colors, the colors that work in ColorBrewer, and the things that look good on the page,” Park said, noting that she'll tinker with the colors in Illustrator until she’s happy with the palette. “Usually my trick is to tweak the shades a little bit so that the greens have a little bit more blue in them,” Park added. “But the problem with that is that if you’re greens get too blue then you start to look like you have a political map or the colors just don’t read as intuitively.”
2. Gregor Aisch’s chroma tool is also useful for optimizing your diverging color palettes. It can help you take two or more colors and generate a full scale of in-between values.
3. Before publishing, you should check your work. Color Oracle and Sim Daltonism both let non-colorblind people simulate colorblindness on their screens.

The great thing about picking a palette, is that once you have it, you can use it again and again.

Taking a few minutes before publishing a project to make sure it’s colorblind friendly is an easy way to make your work have a bigger impact.

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If you are not suffering from a color vision deficiency it is very hard to imagine how it looks like to be colorblind. The Color BLIndness Simulator can close this gap for you. Just play around with it and get a feeling of how it is to have a color vision handicap.

As all the calculations are made on your local machine, no images are uploaded to the server. Therefore you can use images as big as you like, there are no restrictions. Be aware, there are some issues for the “Lens feature” on Edge and Internet Explorer. All others should support everything just fine.

So go ahead, choose an image through the upload functionality or just drag and drop your image in the center of our Color BLIndness Simulator. It is also possible to zoom and move your images around using your mouse – try it out, I hope you like it.

If there are any issues with the Color BLIndness Simulator please send a note through the contact page. Thanks. If this simulator is not correctly working for you, you could still try the old version which can be found at Coblis.v1 – Color Blindness Simulator.

As it is not not so easy to describe color blindness it comes in handy, that some smart people developed manipulation-algorithms to fake any form of color vision deficiency. The algorithms transform any picture into the same picture as seen by red-, green-, blue- or completely colorblind people.

Sim Daltonism Android

I would like to thank Michael from ColorJack for providing the color blindness matrix, which was used for the first version of the Color BLIndness Simulator. The actual version ist based on the jsColorblindSimulator-Project developed by MaPePeR. He made it possible to use just client resources and added some very cool features like pan&zoom. At the moment the HCIRN Color Blind Simulation function is used, which is freely available for non-commercial use.

Sim Daltonism For Mac

The Color Blind Simulation function is
copyright (c) 2000-2001 by Matthew Wickline and the
Human-Computer Interaction Resource Network ( http://hcirn.com/ ).
It is used with the permission of Matthew Wickline and HCIRN,
and is freely available for non-commercial use. For commercial use, please
contact the Human-Computer Interaction Resource Network ( http://hcirn.com/ ).