24 Sep PDFs and Accessibility
The PDF (Portable Document Format) was originally created by Adobe in the early 1990s. A PDF file is essentially a digital image of a document that a person can view, print, or send to someone else. PDFs are useful because they look the same no matter what device they are viewed on and can be used to preserve documents in their current state. We use PDFs for many types of content today, and all people using computers should be able to access them, including those with disabilities.
Creators can follow several steps to ensure that PDFs are digitally accessible to everyone. An accessible PDF meets certain technical criteria, making it usable by people with challenges like blindness or low vision. Certain strategies used to improve PDF accessibility are noticeable, such as color contrast. But most PDF accessibility is invisible and won’t affect design. Think of the majority of accessibility features like the foundation of a house, the structure that exists behind the scenes.
PDF accessibility is primarily created through the “tagging” of headings, paragraphs, and images, allowing users to easily move from section to section or element to element, like navigating songs on a CD. Tagging also ensures that screen readers will read content in the intended order.
Below are some additional features that can improve PDF accessibility:
- Alternative Text for Images (alt text): Image descriptions that are only available when someone is using assistive technology, like a screen reader. Alt text is different from captions, which are visible near an image to offer additional information about what is shown. Alt text is necessary for blind people.
- Color Contrast: Sufficient contrast between foreground and background colors to help those with color blindness (must have a 4.5:1 contrast ratio at Level AA under the WCAG guidelines and a 7:1 contrast ratio at Level AAA).
- Heading Structure: A structure that organizes content into sections that can be tagged to allow users to jump forward and backward between parts of a document.
- Table Structure: Table tags established in the background of a table that indicate which parts of the table are headers and which are data cells. These tags are not visible.
Accessible PDFs help all users because accessibility features improve navigation and organization, and allow assistive technology to provide accurate and comprehensive information to people with disabilities. Emergent Learning can help you design accessible PDF documents to meet your needs. Please email us at [email protected] to learn more.