Power Point - Color Contrast

PowerPoint Accessibility Technical Standard 8: Color & Contrast

The “Why” Behind the Standard

There are two primary reasons color is a major focus of digital accessibility:

1. Contrast: If text color is too similar to the background color, it becomes unreadable for many users.
2. Color as Meaning: If color is the only way information is conveyed (for example, “The answers are in red”), students who are color‑blind or using screen readers will miss that information.

The Goal: Ensure all text is easy to read against its background and that no information is lost if color is removed.

Step 1: Meet the Contrast Ratio Requirement

For WCAG AA compliance, text must meet the following contrast ratios:

• 4.5:1 for normal text
• 3:1 for large text

1. Avoid: Light gray text on a white background, or yellow text on a white background.
2. Best Practice: Use dark text on a very light background, or white text on a very dark background.
3. Helpful Tools: Use tools such as the TPGi Colour Contrast Analyser or the WebAIM Contrast Checker to test your color combinations.

Step 2: Do Not Use Color Alone to Convey Meaning

Always provide a secondary indicator—such as text, symbols, or patterns— to identify important information.

• The Problem: “The red items are mandatory and the green items are optional.”
• The Solution: “Mandatory items are marked with an asterisk and labeled ‘Mandatory’ (* Mandatory).”
• The Logic: If the slide were printed in black and white, would the student still understand the meaning? If not, the slide is inaccessible.

Step 3: Managing Text Over Images

Placing text directly over a busy image often causes contrast failures, since parts of the image may be light while others are dark.

1. The Fix: Place a solid or semi‑transparent shape (such as a dark gray rectangle) behind the text to create a consistent background.
2. Alternative: Move the text into a dedicated content placeholder next to the image instead of placing it on top of the image.

Step 4: Using Built‑in Themes Carefully

PowerPoint themes and Design Ideas are not always accessible. Some include low‑contrast color combinations.

1. How to Check: Apply a theme, then immediately go to Review > Check Accessibility.
2. Look for warnings such as “Hard‑to‑read text contrast.”
3. If a slide is flagged, adjust the text or background color until the warning disappears.

Step 5: High Contrast for Charts and Graphs

Do not rely on different shades of the same color (for example, multiple shades of blue) to distinguish data.

1. The Fix: Use clearly different, high‑contrast colors (for example, blue, orange, and green).
2. Pro Tip: Add patterns or text labels directly to bars or pie slices so meaning is clear without color.

Step 6: Final Validation

1. Go to Review and select Check Accessibility.
2. Review all items listed under “Hard‑to‑read text contrast.”
3. Manual Check: Switch your monitor to grayscale (black and white). If charts, links, and emphasis still make sense, the standard is met.

Quick Checklist for Color & Contrast

• [ ] Is all text high‑contrast (for example, black on white or white on dark blue)?
• [ ] Did I avoid using color as the only indicator of importance?
• [ ] Are charts labeled with text or patterns in addition to color?
• [ ] Did I run the Accessibility Checker to catch contrast warnings?