At Visually, we try our best to make sure the work we produce is accessible to as many people as possible, no matter their capabilities, or disabilities. Unfortunately, there are limitations to what we can do. Data visualization is by definition, a practice that only works for sighted individuals.
There are, however, varying degrees of sightedness. And there are things that can be done to improve visualizations for individuals with less than optimal sight abilities.
Color blindness is a widespread phenomenon, affecting between 7% and 10% of males. That is a lot of people. If someone told you that 10% of your potential customers couldn’t use your product as it was designed, you would head straight back to the drawing board. Fortunately, most of the design changes to make it possible for colorblind individuals to use a visualization are really simple to achieve.
There is a ton of information around about colorblindness, and there are some great simulators that show what an image looks like to a colorblind person. One surefire way to avoid colorblindness issues is to choose color scales and palettes appropriately. This is absolutely necessary when a color scale is the only visual encoding of a data dimension, but in many cases, there are other ways to fix the issue.
Color schemes with red and green aren’t always bad for accessibility. Often times, spatial relationships or effective labeling can provide equally effective ways of addressing colorblindness. (Whether or not red and green is a good aesthetic choice is still up for debate.)
Generally poor vision, especially cataracts and far-sightedness, is another issue that can be dealt with through design. Using highly contrasting colors, and font choices with highly differentiated letters, high x-heights, and appropriately large sizes can help to alleviate issues for people with blurry or obstructed vision.
As data visualization becomes more and more prominent in our culture, it is important to remember to design for as many people as possible. For those with sight impairments, some relatively simple changes can make a world of difference.