Setting Appropriate Color Contrast
Providing sufficient color between foreground and background is important to many user groups but especially to those with low vision and color blindness. Color contrast applies to any text or images of text. Text styled below 18-point font must have a color contrast ratio of 4.5:1, unless bolded. Text styled at 18-point font or greater, or at least 14 point and bolded, must have a color contrast ratio of 3.0:1. Resources for verifying the contrast between foregrounds and backgrounds can be found under Color Resources on the VHA OHI 508 Office’s Resources page.
Examples of color contrast
Changing the text color
The easiest way to improve the contrast of text (not images of text) in a PDF document is to change the foreground color (or the color of the text itself). To change the color of the text in Acrobat X, follow the steps below.
- From the Tools pane, under Content, navigate to and activate the Edit Document Text option.
- Select (highlight) the text in the document which needs to be modified.
- If a TouchUp error dialog appears stating the some fonts are not available and a substitute is going to be used, navigate to and activate the OK button.
Most of the time the look and feel of the text is not modified in a manner that is disruptive.
- Activate the Context menu of the selected text, and select Properties… from the menu.
- Verify the Text tab is the active tab in the dialog.
- Navigate to and activate the Fill color-picker button and select a desirable color.
- Navigate to and activate the Close button.
- Verify the color of the selected text has changed in the document.
- Perform appropriate tests to ensure the new foreground color meets sufficient contrast ratios in relationship to the background.
- Repeat the steps above to continue changing and verifying the contrast.