How to Fix PAC Error: Figure Element Has No Bounding Box in PDF
Question details
The user needs to resolve an accessibility error in the PDF Accessibility Checker (PAC) stating that a figure element has no bounding box.
- Product
- Device & OS
- not provided
- Scenario
- Checking PDF accessibility compliance using the PAC tool and encountering errors on specific images.
- Observed behavior
- PAC reports a failure indicating that figure elements, often small images or screen captures, lack a bounding box due to incorrect tagging.
Ensure you have a PDF accessibility editor or tagging tool installed, and always save a backup copy of your original PDF document before modifying its structural tags.
Delete and Retag the Faulty Figure Element
This method involves removing the corrupted tag and manually retagging the image to generate a correct bounding box coordinate.
Bounding box errors usually occur when PDF generation tools fail to assign proper spatial coordinates to small graphics. Manually recreating the tag forces the software to recalculate and assign the correct bounding box.
Open your PDF in an accessibility editor and find the faulty figure tag in the document's structural tag tree.
Right-click the problematic figure tag, view its properties, and copy its existing Alternative Text (Alt Text) to your clipboard or a notepad.
Delete the faulty figure tag directly from the structure tree to remove the corrupted element.
Select the physical image in the document view pane and use the tagging tool to recreate it as a new 'Figure' tag.
Open the properties of the newly created figure tag and paste the Alternative Text you saved earlier, then save the document.
Upgrade to the Latest Version of PAC
Using an outdated version of the PDF Accessibility Checker may result in false positives or unclear error reporting.
Edit and Manage PDF Elements with WPS Office
WPS Office provides robust PDF editing capabilities, allowing you to easily adjust images, modify text, and manage document elements to help ensure your PDFs are well-structured before running accessibility checks.
- 1. Open PDF in WPS: Launch WPS Office and open your problematic PDF file from the home screen.
- 2. Access PDF Edit Mode: Navigate to the 'Edit' tab and click on 'Edit PDF' to make all document elements selectable.
- 3. Adjust Problematic Images: Select the small images or screen captures causing issues to resize, reposition, or delete and re-insert them properly.
- 4. Save the Document: Click 'Menu' and select 'Save As' to export your corrected PDF document, ready for an updated accessibility check.
Frequently Asked Questions
What is a bounding box in a PDF document?
A bounding box is a defined, invisible rectangular area in a PDF that outlines the exact position, width, and height of an element like an image or text block. It is essential for accessibility tools to properly interpret the layout and document structure.
Why does PAC report this error primarily for small images?
Small images or screen captures often get incorrectly tagged during the automated PDF conversion process from software like Word or PowerPoint. The conversion engine might fail to generate the correct positional coordinates (the bounding box) for these minor elements.
Can I simply ignore bounding box errors if the document looks fine?
If you require strict ADA compliance, PDF/UA, or WCAG certification for your documents, you cannot ignore this error. Accessibility screen readers rely on precise bounding boxes to navigate the page and describe figures accurately to visually impaired users.
