Optical Character Recognition (OCR) Tool in Canvas Ally
What is OCR?
Optical Character Recognition (OCR) refers to technologies that allows images of text to be converted to actual text. OCR allows for the extraction of text content from old documents, infographics, photos of signs, PDFs of scanned files and any situation when text is embedded within an image.
OCR Tool in Canvas Ally:
Key Features of the Ally OCR Tool in Canvas:
- Automatic Conversion: When an instructor encounters a scanned PDF (image-only) in Canvas, Ally allows them to download a machine-readable "OCR'ed" version.
- Accessibility Scoring: Ally provides instructors with a color-coded gauge (red, orange, green) to indicate the accessibility of documents and images. Ensure to check each document.
- Instructor Guidance: Ally gives step-by-step instructions on how to fix accessibility issues, such as converting a scanned document to a structured, searchable text format.
- Availability: The tool is available to instructors, allowing for on-demand conversion of files within the course.
- Not a Permanent Fix: While Ally creates an accessible version for download, it is recommended that instructors replace the original scanned file with the OCRed version for a permanent fix. Also, it is recommended to check the document using Adobe's Accessibility Checker after the document has been OCR'ed using Canvas Ally, see all instructions below.
How to Test a PDF for Accessibility?
Test: Image vs. Text
Within a PDF, it is important to determine whether text is selectable and therefore more accessible or from a scan where the text is actually part of an image.
Pre vs. Post OCR.
When text is embedded within an image, it cannot be copied and pasted into another document. Once it is OCR'ed, the text should be searchable and readable.
Check Accuracy
If a PDF appears to be a scan, but with selectable text, you should verify that the text layer is accurate. In some cases, the output may need to be corrected following the steps below. Also, the PDF tagging and accessibility features will still need to be checked for accuracy.
How to check Accessibility of PDF's in Canvas Ally?
When using Ally to check materials in a Canvas course, you will sometimes find PDFs that earn a low or medium accessibility score and see the message This PDF is scanned. The first thing you can do to begin to remediate this document is to use Ally’s alternative formats feature to create an OCR'ed version of the PDF, that can then be put in place of the scanned PDF. Once that has been done, the accessibility report should indicate improvement in the document’s accessibility, as well as other improvements that can be made to the raise the score higher.
Turning Scanned PDFs into OCRed PDFs in Canvas
- Once you have identified that a file is a scanned pdf, click Files in Course Navigation.
- Hover over the name of the file in question to make the
option icon appear to the far right. - Click the option icon and select Alternative formats.
- Close the Alternative Formats window using the X in the upper-right corner. In the Files area, click the accessibility score icon next to the file you want to update to open the Ally window.
- Select OCR'ed PDF and click the download button on the bottom right.
- Click the Upload button at the top right and select the downloaded OCR'ed PDF. If the file has the same name, it will open a pop-up window in which you can choose to Replace the original document (which is recommended).
- Once a Scanned PDF is replaced with an OCRed PDF, don’t forget to re-check the new Accessibility Report for the file to determine other remediation that can be done.
- Accuracy: The quality of the OCR conversion depends on the quality of the original document.
- Password Protection: Ally cannot generate alternative formats for password-protected files.
Use the Adobe Acrobat Pro Accessibility Checker on all your PDFs
This tool will tell you all of the remaining issues with your PDF.
Instructors should note that tagging and OCR’ing your PDFs will significantly increase the Ally course accessibility score and will also give basic accessibility to students while you work through the nuanced accessibility aspects to make it fully accessible.