Canvas Best Practices for Scanned PDFs

This article will describe common issues with scanned PDFs and best practices for this type of online content.

Overview

A best practice for online content is to avoid using scanned documents whenever possible. Scanned texts are inaccessible to screen readers which can create many challenges for students. In Canvas, sometimes Ally will flag a scanned document as being inaccessible because it does not have any Optical Character Recognition (OCR).

Example of an Canvas Ally message:

The document is scanned but not OCRed

These documents are either entirely scanned or contain pages that are scanned. Screen readers are unable to convert an image into words, even if the image only consists of text, so people with screen readers or other assistive devices will not be able to read those pages. Scanned documents, especially those of poor quality or those containing handwriting, can be difficult to read for everyone. They also have other usability issues such as not being able to search inside the document.

The document is scanned but not OCRed

These documents are either entirely scanned or contain pages that are scanned. Screen readers are unable to convert an image into words, even if the image only consists of text, so people with screen readers or other assistive devices will not be able to read those pages. Scanned documents, especially those of poor quality or those containing handwriting, can be difficult to read for everyone. They also have other usability issues such as not being able to search inside the document.

Tips for finding other formats of the resource:

Try to find a text version of the document online. Google has very helpful ways to do this. Try searching "[Name of file] filetype:pdf"

If you do this, make sure the document is not also scanned! If you can't tell if the file is scanned or not, try to highlight some of the text. If you can't highlight the text, don't use the file.

As a last resort, Ally will automatically perform optical character recognition (OCR) on the document to try to better identify text elements. Unfortunately, this is not a final solution, so it won't improve your score. You'll want to replace the scanned version when possible

Replace the PDF with an updated version that has been OCRed

Boise State University provides Adobe Acrobat Access to Faculty which allows for editing PDFs.
How to edit scanned documents:
- Open a PDF file containing a scanned image in Acrobat for Mac or PC.
- Click on the “Edit PDF” tool in the right pane. Acrobat automatically applies optical character recognition (OCR) to your document and converts it to a fully editable copy of your PDF.
- Click the text element you wish to edit and start typing. New text matches the look of the original fonts in your scanned image.
- Choose “File” > “Save As” and type a new name for your editable document.
Re-upload the PDF into Canvas, replacing the original.

Content adapted from the Blackboard Ally Communication and Adoption Toolkit - CC BY 3.0

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