Colorblindness, WAS: ARGH! Question about screen captures

[David Loveless]

Ah... The colorblind issue in usability.

There are many misconceptions about colorblindness, even a few that are
promoted right here. As a colorblind person, it is on the forefront of my
mind when I develop my documentation. The single best solution is to avoid
color in all aspects. You are almost guaranteed to have a problem no matter
the colors you use simply because colorblindness can affect any and all
colors even for your simple red/green colorblind people. But if you cannot
avoid the color, at least follow some basic tips:

1. Never ever ever use red and green together. Just don't do it.

2. Never use red or green on a gray background. I have told the story many
times of working on a language training project for several months before I
realized that incorrect user responses were marked with a red X. I just
didn't know because the red X was placed on a gray background.

3. Never use varying shades of the same color to distinguish differences.
Another example from my experience was a training manual where each chapter
was distinguished by a varying shade of brown. Again, I had no idea that
there was a difference.

4. If you must use color, provide a black barrier between the colors. Black
helps define the color edge and gives shape to the color. Going back to tip
2, if those red Xs would have had a black outline, I would have seen them
without any problem. True, I would have not seen the red probably, but I
would have seen the shape.

5. Always provide another method of distinguishing something other than
color. There's a reason links in web pages use color, bold, and underline.

If you'd like to read a good, mythbusting explanation of what colorblindness
is, I wrote a brief article for my blog on the subject. The link is below:
http://daveloveless.wordpress.com/2007/04/23/into-the-deep-red-sea-a-journey-in-colorblindness/