How to add or change an image’s alternate text within a PDF.
Why add Alt Text to images? Adding alt (alternate/alternative) text to images allows screen readers
(assistive technologies) to provide visually impaired readers with a better understanding of a
document’s contents overall.
1. Open your PDF document in Acrobat Pro. The quickest way to determine if the images in the file
have alt text embedded within them is to move your mouse over them slowly. If the tooltip
turns to crosshairs with a line of highlighted text next to it, then the image has alternate text
embedded within it.
2. If there is no line of highlighted text, or if you have a long document with many images that
need to be batch-checked, you will have to run an Accessibility Report to determine the status
of the images.
3. To run the report, you need to use Acrobat’s Accessibility tools, which you will add now if they
have not already been added to the toolbox to the right of your main document pane.
This toolbox is located to the
right of your document pane.
4. To locate the Accessibility tools click on the More Tools button at the bottom of the toolbox list.
Then, type “Accessibility” into the search field of the Tools window. Click add, and now, close
the Tools window and return to your document by clicking on the tab above your document
pane which displays your document’s title.
5. Returning to the toolbox to the right of your document pane again, it now incorporates the
Accessibility tool at the bottom of the list.
6. Click on it to open its specific toolset.
7. Next, in the Accessibility Toolbox, click Full Check. This will open the
Accessibility Checker Options pop-up window. Leave all the options ticked on, and click the
Start Checking button.
8. Next, an Accessibility panel will open to the left of your document pane. In this example, the
Checker has allerted you to one issue relating to Alternate Text.
a. Twirl down the the arrow on that alert. Once opened, the image (figure) that is problematic
will have a red-x next to it. Right click on the error alert.
b. A drop down menu will open and offer a “Fix” option – click Fix.
c. A pop-up window will appear which will prompt you to enter Alternate Text for the figure.
Enter a brief sentence or two in the prompt. Ideally your text phrase should begin with
“Image is of a …” Your reader will then recognize that what is being read is separate from
the main text of the document and that an image is being described. Click Save & Close.
9. Recheck the Accessibility pane to the left of your document window now. The Alternate Text
Alert is resolved.
10. Save your document and have your screen reader do a test reading. If the reader does not read
the image’s alternate text, save the document, reopen it, and have it read the document again.
11. If you do not have JAWS or another screen reader application, Acrobat can also read your
document for you. While your document is still open, go to View → Read Out Loud → Activate
Read Out Loud→ View (again) → Read Out Loud → Read to the End of Document.
