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Learning how to choose accessible PDFs for your course takes a little bit of knowledge about what makes PDFs accessible. The first thing to know is that PDF accessibility is complex. If you can provide content as a Word document instead of a PDF, that is often preferable from an accessibility perspective.

Assessing PDF Accessibility

The main recommendation to follow with PDFs is to avoid using PDFs created from scanned paper documents. Try to use PDFs that were created from digital files instead. 

There are two primary types of accessibility issues with scanned PDFs:

1. Lack of selectable text

2. Poor image quality

Lack of selectable text

“Selectable text” refers to text that can be interacted with by users, such as by highlighting and copying the text. Documents should have selectable text in order to be read with assistive technology. Selectable text makes a document more usable for all students, not only students with disabilities. Scanned documents can be processed with optical character recognition (OCR) in order to convert an image of text into selectable text, but OCR tools are not perfect, and there will usually be some errors in the conversion process.

Poor image quality

The second main problem with scanned PDFs is that they typically have poor image quality that impacts usability and accessibility, even after being processed with OCR. Text that is blurry, is misaligned, has stray marks, or has any type of handwriting or highlighting can be difficult for all students to read. For students who use assistive technology, these issues can make the text completely inaccessible.

What To Do About Scanned PDFs

If your PDF was created from a scanned document, try to locate an alternate version of the material. Most journal websites provide a downloadable text-based PDF for their articles that is more accessible than a scanned image PDF. Try doing a search using the Norlin OneSearch service to see if there’s a text-based version you can use. If your content is only available in a paper book format, acquire the cleanest possible copy of the book (free from underlines, handwritten notes, etc.)

If it is necessary to use a scanned document, choose the cleanest version available, and ensure that the text of the file is selectable. You can check if a PDF’s text is selectable by trying to highlight and copy individual words. If the text is not selectable, you can use software with OCR capabilities on the document to generate text from the image.

Using Optical Character Recognition (OCR)

There are a variety of easy ways to run OCR on a document; one way is to use a free OCR conversion tool available to campus staff, faculty, and students. The quality of the content that is produced by SensusAccess’s OCR will depend on the image quality of the document you are using; it will likely not produce a perfect result, and it will not meet standards for full accessibility because it will still lack headings, image descriptions, and other features. Nevertheless, an image-based PDF that is run through SensusAccess will be much more accessible than one that is not.

Why Does PDF Accessibility Matter?

Students who use assistive technology like screen readers often require remediation of inaccessible PDFs before they can access the material for class. Please keep this in mind if you are selecting a new PDF for students to read that was not on the syllabus; some students may require time for Disability Services to convert the material if it is not fully accessible. It is best to provide at least two weeks of lead time for any new reading material during the semester.

Selectable text makes a PDF more accessible for students who use assistive technology, and it can also make the document more usable by all students. Selectable text means that students can copy-paste the content, highlight important concepts, and more. 

Further Training

You can further improve the accessibility of a PDF using, which is available for free to faculty. For training on this or for other questions about PDFs, please contact the Digital Accessibility Office at DigitalAccessibility@colorado.edu.