Ensure Sufficient Contrast Between Text and Background
Whether you’re creating content in web pages, Word documents, or InDesign documents, you need to ensure that the text is easy to read against the background. This is particularly important for people with low vision, who often need much more contrast than the average person in order to read the text.
There are several color contrast checkers available online. Use these tools to determine if your color choices pass the minimum threshold set by the Web Content Accessibility Guidelines (WCAG). The guidelines specifically say that the contrast ratio must be 4.5 to 1 or greater for regular text, or 3 to 1 for large text (defined as 18pt regular font or 14pt bold font). It is important to use one of the tools to check the level of contrast. Simply looking at the text and guessing the contrast is not sufficient for accessibility purposes.
Don’t Rely on Color Alone to Convey Information
It’s OK to use color, but it’s not OK to use color as the only way to convey meaning. For example, if you want to use a red outline around a section of the document to mean that you shouldn’t do the things mentioned in the red box, you can do that, but you must also have some text explicitly saying, “Don’t do these things” (or whatever wording is appropriate for the situation).
If you use color alone to convey information, you make it impossible for blind users to know what you mean. If you happen to choose color combinations that are difficult for people who are color-blind—like red and green—you will make it difficult or impossible for them to figure out the meaning too. Any visual way of communicating information requires a text equivalent.