The term color blindness is actually misleading. Most people who are “color blind” are not blind to all colors, but really have a color deficiency that makes it hard for them to see differences between some colors.
Different types of color blindness — There are many different kinds of color blindness, but the most common is a difficulty distinguishing between reds, yellows, and greens. This is called “red-green” color blindness. Other forms, such as problems distinguishing blues from yellows, or where everything looks grey, are very rare.
What people see – Let’s compare what people see who have different types of color blindness. I’ve put three different screen captures from a post at this blog. The first picture below is how it appears to someone who has no color blindness, the second is how it appears to someone with red-green color blindness, and the last one is how it appears o someone with blue-yellow color blindness.
When colors become a communication problem — So what’s the big deal you might be saying? What colors you use in your photos, illustrations, maps, etc, can become problematic if you are trying to communicate information via the colors. For example, here is a map of winter driving conditions in Wisconsin that has color coding. And below that is a map that shows what it looks like if you have red/green color blindness.
If you are going to use color as a way to communicate — then you need to have a redundant coding scheme, for example color AND line thickness so that people who are color blind will be able to decipher the coding without needing to see specific colors.
Or pick colors that work or everyone — Another approach is to pick a color scheme that will work for people who have the various types of color blindness. In the example below they have purposely picked colors that look the same for people regardless of the type of color blindness they have, and even if they are not color blind.
You can test your colors — You can use websites to check for color blindness effects.
What do you think? What approach do you use to make sure your images work for people who are color blind?