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Fix Cannot Highlight Scanned PDF Text with Apple Pencil on iPad Pro
Question details
The user is unable to use the text highlighter tool on a scanned PDF using an Apple Pencil on an iPad Pro.
- Product
- PDF Reader / Adobe Acrobat Reader
- Device & OS
- iPadOS
- Scenario
- Attempting to annotate and highlight text within a scanned document using an Apple Pencil.
- Observed behavior
- The highlighter tool fails to select or highlight the content because the scanned document consists entirely of images without recognized, selectable text layers.
Verify if your PDF contains selectable text by attempting to long-press a single word with your finger. If the word does not highlight in blue, the document is an image-based scan and will require OCR conversion or freehand drawing methods.
Use OCR to Convert the PDF to Selectable Text
Convert the image-based scanned PDF into a searchable document using Optical Character Recognition (OCR), allowing standard text highlighters to work.
Text highlighters in PDF applications rely on selectable text layers to snap to the words. Scanned documents lack this layer. Using an OCR tool extracts the text from the image, bridging this gap.
Import your scanned PDF into a PDF editor that supports OCR, such as WPS Office or Adobe Acrobat Pro on your iPad Pro.
Locate the 'OCR' or 'Recognize Text' tool in the app's menu and run the process on your document.
Save the newly generated file, which now contains a selectable text layer over the scanned images.
Select the text highlighter tool and drag your Apple Pencil across the newly recognized text to highlight it seamlessly.
Use the Scribble Workaround in Acrobat Reader
Apply a simple Apple Pencil gesture trick to force the highlighting tool to engage on tricky or partially recognized text.
Use the Freehand Draw Tool as a Highlighter
Bypass text-selection limitations entirely by using a freehand drawing tool with customized opacity to manually paint over the scanned text.
Highlight Scanned PDFs Easily with WPS Office OCR
WPS Office provides robust PDF editing tools for iPad Pro users. With built-in OCR capabilities, you can quickly convert unselectable scanned images into fully editable text, making Apple Pencil annotations and highlighting effortless.
- 1. Download WPS Office: Install WPS Office from the App Store on your iPad Pro.
- 2. Open and Run OCR: Open your scanned PDF, tap 'Tools', and select 'OCR' to extract the text.
- 3. Save and Highlight: Save the text-recognized document and use the highlighter tool with your Apple Pencil to mark important sections easily.
Frequently Asked Questions
Why does my Apple Pencil only draw ink instead of highlighting text in PDFs?
If your Apple Pencil draws solid ink lines instead of snapping to text, you are likely using a freehand pen tool, or the PDF is a scanned image without a recognized text layer. Use an OCR tool to extract text, or ensure the correct text-highlight tool is selected.
Does iPad OS have built-in OCR for PDFs?
iPadOS features Live Text, which can occasionally recognize text in images, but it is often inconsistent for multi-page scanned PDFs inside third-party reader apps. Dedicated OCR software like WPS Office provides much more reliable text extraction.
Can I use Apple Pencil to highlight PDFs without buying premium apps?
Yes. Many free or freemium PDF readers, including WPS Office, support Apple Pencil markup. If the document is a scan, you can use the freehand drawing tool with lowered opacity to highlight text without needing to purchase an OCR subscription.
