The Portable Document Format (PDF) is originally aimed for exchanging documents in a way that the arrangement of the content is preserved whichever device is used for reading. This is a great choice for sharing read-only educational material like literature and handouts to students.
- Accessibility issues with scanned documents
When scanned documents are saved as PDF without text digitisation then they use to have the following issues:
- Large size. They use to be noticeably large in comparison to digital text files. Pictures of pages > Digital text.
- Poor image quality. Low scanning resolution, dirt and post scan processing can result in a digital document whose text is not recognisable or not magnifiable without pixelation.
- ATs are not able to work with pictures of text. Eg. screen readers.
Lack of navigation. The reader is not able to jump directly to sections or navigate tables.
The non-text elements are not labelled and do not have AltText.
The digitisation procedure is costly. This requires manual post processing to assure that the OCR output correct text and the non-text objects are labelled and described properly.
- Creation of accessible PDF documents
- Make the source document accessible. No matter what editing tool is used (Word, InDesign, …), accessibility best practices and guidelines should be followed.
- Once the source document is accessible it is possible to export it to PDF. In this way there are less accessibility issues that might appear in the output PDF and it is easier to correct.
- Check the accessibility of the export in Adobe Acrobat and repair the remaining accessibility issues. This can be the most costly step because PDF is not intended for editing after it has been rendered. There are guides and documentation that show in detail how to proceed with this last step. The next points introduce how to spot and correct the accessibility issues.
- Check the accessibility of PDF documents
- Do an automated accessibility check. Use Adobe Acrobat Pro by Adobe, CommonLook PDF by CommonLook or Foxit PDF Editor by Foxit, to evaluate and identify any accessibility. This does not detect or correct all issues therefore the following manual checks have to be done too.
- Try to copy a piece of text. If you are not able to copy or paste the copied content to a Notepad then the PDF is not accessible. This happens when the document is made of “pictures” of the pages of the physical document. Think of scanned documents. This issue is hard to solve because it needs an Optical Character Recognition (OCR) procedure. Adobe Acrobat Pro offers tools to do this costly procedure. To know more you may go to the following “Repair the accessibility” section.
- The PDF should provide an outline of its content in the bookmarks panel. You should use this to go directly to specific sections without the need of leafing, or scrolling, until reaching the section sought.
- When you are selecting text, is the selection following the logical reading order or it selects at some point elements in the page that are not meant to be read at this point? If the selection is not working as expected then the reading order of the document is not correct and therefore it is not accessible. Another way to test the accessibility of a PDF document is using a screen reader or with “Read Out Loud” functionality of Adobe Reader or your PDF reader. It should read the content in a logical order.
- Check other common accessibility issues such as:
- colour contrast,
- the content of the alternative text for non-text elements,
- table structure and
- whether the language used is appropriate for the learners.
- Test with AT. I.e. Try to find accessibility issues using a screen reader opening, navigating and reading through the document.
- Repair the accessibility of non-accessible PDFs
- Remediating the accessibility of a PDF document is an expensive task with high risk of not addressing all accessibility issues. Therefore, this approach should be avoided when possible, by following the next point.
- PDFs are created from documents that are meant for editing. The most effective way of getting an accessible PDF document is properly structuring the source document, making it accessible (including setting the language and filling in the necessary metadata) and enabling the accessibility features of PDF when exporting to PDF.
- Adobe Acrobat Pro is the most used tool for fixing the accessibility of PDFs. The procedure is structured generally in 9 fixing stages:
- Document properties.
- Provide alternatives to non-text elements. It might involve OCR.
- Links and interactive elements.
- Tag structure.
- Colour issues.
- Although the procedure is defined and clear, the execution of the different accessibility-fixing steps is not straightforward and it could require some craftsmanship and experience working with the PDF.