All essential images, charts, or graphs must have descriptive alternate text (i.e. alt text, alternative text, or image description). In Adobe Acrobat Pro's tags tree, all non-text content are referred to as Figures. Use the following steps to check or add alternative text to the <Figure> tags.
Step 1. Open the Tags Tree.
Open your PDF. Select View > Show/Hide > Navigation Panes and select the Tags option from the list. This will open the Tags Tree.
Step 2. Open Figure properties.
Within the Tags List, right click the <Figure> tag you want to add alternative text to. Choose the Properties option from the menu.
Step 3. Type the Alternate Text
In Object Properties dialog box, type your descriptive alternative text into the edit box for Alternate Text. Include the most important information first and be as concise as possible. To save changes, choose the Close button.