03 February 2011

Designing for deuteranopes

People tend to use red, green, and blue on white backgrounds, because those are simple colours that are dark enough to stand out. But that can be a problem for deuteranopes.

Deuteranopia is one form of colour blindness. About 7-8% of men are colour blind in one way or another, with red-green colour blindness of some form being the most common. Thus, chances are that at a reasonably sized conference, someone walking past your poster has issues distinguishing colours that most of us take for granted.

Andy Baio has a great post about reading graphics with his “broke-ass eyes,” as he put it. There are some great tips there.

Did you know that Photoshop has a colour-blind simulator? I didn’t.

Even better, Andy points to Vischeck, an online colorblind simulator. I ran several posters that I had previously critiqued through the simulation. Luckily, most of them held up pretty well. Here are a couple of examples (click to enlarge).

The overall effect is much more monotone, but the poster is still quite legible overall.

This one has a more serious issue. The figure in the upper right corner might not interpreted properly by someone who is red-green colour blind.

If you want to use red and green to distinguish data on a graph, make sure that the data is distinguished by some other characteristic than just colour. Don’t use red and green circles; use red circles and green triangles. Don’t use red and and green lines; use a red solid line and a green dashed line.

And you can’t go wrong with good ol’ black text and lines on a white background.

I found that once I was reminded of how common colour blindness is, I became sensitized to it, and started noticing potential problems. A little planning can go a long way in making your posters legible for colour blind people.

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