Did you know there are several different kinds of colorblindness? Some people are completely colorblind, while others are only unable to see red and green, or blue and yellow. Wikipedia states that in the United States alone, about 7% of the male population (around 10.5 million men) has some degree of colorblindness. For this reason, a good design should not rely on color contrast alone to communicate information.
Luckily, there’s a very quick test for seeing if your slides will have sufficient contrast for someone who’s colorblind to be able to understand it. Under the View menu in PowerPoint, there should be an option for Grayscale. By selecting this option, all hues will be removed from the image and you’ll see something akin to total colorblindness. You can now inspect your slides to see if all of the information is still understandable and readable. (You can also achieve the same effect by opening the Print dialog box and choosing grayscale.)
If your design is readable in grayscale, congratulations. Well done. If some elements are unclear or hard to read, you need to find different ways to convey your information.
One good way to make color contrasts show up in grayscale is to play around with the saturation of the colors. Variations of the same hue will still be visible in grayscale due to differences in saturation, as you can see in the two slides below. If your color choices are not visible in grayscale, play around with the colors until they look good both ways.
This is just a real quick solution for identifying and solving design issues related to colorblindness. I’m sure there are other solutions out there. What methods do you use?