Fix PDF Highlighting Selecting Large Areas After OCR
Question details
The user is experiencing an issue where attempting to highlight a few words in a PDF selects large, unintended sections of the page.
- Product
- PDF Editor
- Device & OS
- not provided
- Scenario
- Highlighting text in a scanned or OCR-processed PDF document.
- Observed behavior
- The highlight tool selects large blocks of the page instead of the specific words intended, often due to inaccurate OCR text regions or complex document layouts.
Check if your PDF is a scanned document that has recently undergone Optical Character Recognition (OCR), as overlapping text boxes from OCR are the most common cause of irregular text selection.
Use the Freeform Highlighter Tool
Bypass the text-selection glitch by using a freeform drawing tool to manually highlight areas.
When standard text highlighting fails due to invisible OCR layout boxes, switching to a freeform tool allows you to visually mark the document without relying on the underlying text recognition data.
Locate and select the freeform highlighter or drawing marker tool in your PDF editor's annotation menu.
Increase the line thickness of the tool in the properties menu so it matches the height of the text you wish to highlight.
Hold down the 'Shift' key and click and drag your cursor over the text to draw a perfectly straight highlight line.
Rerun OCR with Adjusted Settings
Re-process the document to create more accurate text regions for standard highlighting.
Easily Highlight and Edit PDFs with WPS Office
WPS Office provides an advanced PDF editor with highly accurate OCR capabilities and versatile annotation tools, making it easy to highlight text precisely without layout glitches.
- 1. Open your PDF: Launch WPS Office and open your scanned or problematic PDF document.
- 2. Use the Highlight tool: Go to the 'Comment' tab and select the 'Highlight' tool to attempt standard text highlighting.
- 3. Perform accurate OCR: If highlighting selects large areas, navigate to the 'Tools' tab and click 'OCR' to re-recognize the text accurately.
- 4. Apply manual highlights: Alternatively, use the 'Area Highlight' tool under the 'Comment' tab to manually draw a highlight box over any section, bypassing text selection entirely.
Frequently Asked Questions
Why does OCR cause highlighting issues in PDFs?
Optical Character Recognition (OCR) attempts to identify text in scanned images and creates invisible text boxes over the image. If the document layout is complex, the software may group unrelated words or create overlapping bounding boxes, causing the highlight tool to select entire blocks instead of single words.
Can I remove OCR from a PDF to fix highlighting?
Yes, you can often revert a PDF to an image-only state by 'printing' it as a new PDF using the 'Print to PDF' function. After flattening the file this way, you can use freeform highlighting tools without text box interference.
How do I draw a straight highlight line manually?
In most PDF editors that feature a freeform drawing or highlighting tool, you can hold down the Shift key while clicking and dragging your mouse. This forces the software to draw the line perfectly straight horizontally or vertically.
Is there a way to highlight scanned PDFs without using OCR at all?
Yes, you can use Area Highlight tools or draw semi-transparent colored rectangles over the text. These act as manual highlights and rely purely on visual placement rather than recognizable text data.
