Color can have a big impact on the understanding of content and the information it portrays. This is not only true for low vision users, but also users with color blindness. The two primary types of color blindness, red-green and blue-yellow, cause individuals to have trouble differentiating between these two colors. It’s important not to use these colors together when trying to convey meaning.
In the example above, the word “important” is green to differentiate it from the rest of the sentence. This differentiation will not be visible for users that are color blind, however. This differentiation will not be visible even for users who are not colorblind if the document is printed in grayscale. To make the word stand out, you could bold the word “important” instead.
Low vision users may need a higher contrast of colors in order to effectively understand your message. This is also true for PowerPoint slides -- higher contrasting colors in slides aid in making content more visible to all audience members in a room with varying lighting conditions. Accessibility standards require contrast ratios to be at least:
- 4.5:1 for normal text (14-16 pt)
- 3:1 for larger text (14 pt bold or 18 pt)
Color pieces that are accessible adhere to two key rules:
- Provide ample contrast between foreground and background colors
- Do not rely on color alone to convey information
If adjusting colors, check color contrast for various foreground and background colors by using the color contrast checker.