How to Prevent Acrobat OCR from Increasing PDF File Size
Question details
The user needs to find a way to perform OCR on scanned PDF documents in Adobe Acrobat without experiencing a massive increase in file size or blurry text.
- Product
- Adobe Acrobat
- Device & OS
- not provided
- Scenario
- Running OCR (Optical Character Recognition) on scanned PDF documents to create searchable or editable text.
- Observed behavior
- When OCR is applied, the PDF file size balloons significantly (e.g., from 640 KB to multiple megabytes), and text quality sometimes degrades.
Verify your scanner's default resolution settings and ensure you have an unmodified backup of the original scanned PDF before testing different OCR and compression adjustments.
Change OCR Output Style to Searchable Image
Switching the OCR output style prevents Acrobat from replacing the original scanned image with heavier editable font elements.
Acrobat offers different output styles during the OCR process. The 'Editable Text and Images' option attempts to replace scanned text with system fonts, which can drastically increase the file size. Using 'Searchable Image' overlays an invisible text layer instead.
Launch Adobe Acrobat, open your scanned PDF document, and navigate to the 'Scan & OCR' tool from the right-hand panel.
Click on 'Recognize Text' in the top toolbar and select 'In this File'. Then, click the 'Settings' gear icon.
In the Settings dialog box, locate the 'Output Style' dropdown menu and change it from 'Editable Text and Images' to 'Searchable Image'.
Click 'OK' to save your preferences, then click the 'Recognize Text' button to process the document.
Apply PDF Optimization and Downsampling
Use the built-in PDF Optimizer to compress images and reduce the file size after the OCR process is complete.
Use WPS Office for Lightweight PDF OCR and Compression
WPS Office provides an efficient built-in PDF editor with highly accurate OCR capabilities. It allows you to extract or search text from scanned documents seamlessly while providing powerful compression tools to keep your file sizes incredibly small.
- 1. Open your PDF in WPS Office: Launch WPS Office and open your scanned PDF document in the PDF editor.
- 2. Run the OCR tool: Navigate to the 'Tools' tab and select 'OCR' to recognize text in your scanned pages.
- 3. Save as a searchable document: Choose the option to create a searchable PDF, ensuring the file remains visually intact.
- 4. Compress the final file: If you want to reduce the size further, click 'Compress' under the 'Tools' tab to instantly shrink the PDF.
Frequently Asked Questions
Why does OCR drastically increase my PDF file size?
OCR can increase file size because certain output styles, like Editable Text, attempt to replace background pixels with custom fonts and higher-resolution patches. This process often introduces complex data structures that make the file much heavier.
What is the best scanning resolution for OCR without inflating file size?
A scanning resolution of 300 DPI is generally recommended. It strikes the perfect balance, providing enough clarity for accurate text recognition while keeping the initial image file size relatively small.
How does the 'Searchable Image' OCR option differ from 'Editable Text'?
The 'Searchable Image' option simply overlays an invisible layer of text on top of your original scanned image, which keeps the visual unchanged and the file size smaller. 'Editable Text' actually modifies the document to replace the scanned text with editable system fonts.
