Quick answer
Local Scanned PDF tools are more private and work offline; online tools save installation but files leave your device. A scanned PDF is images; OCR is required for search/copy.
Why it matters
Use local for sensitive files; online is fine for small temporary ones.
300dpi is usually enough.
Step by step
- Check for a text layer: if text is selectable/copyable, OCR may be unnecessary.
- For scans, raise resolution/contrast and deskew.
- Pick the right language (Chinese/English/mixed) and only the needed pages.
- Proofread numbers/amounts/dates/names; don't trust OCR blindly.
- Export TXT/copy, keep the original PDF and a proofreading record.
Common mistakes
- OCR-ing a PDF that already has a text layer and adding errors.
- Low-resolution/skewed scans producing poor accuracy.
- Using one language for mixed Chinese/English pages.
- Not proofreading amounts/dates/IDs before importing.
Checklist
- Text layer vs scan determined.
- Resolution/orientation/contrast handled.
- Language/page range chosen correctly.
- Numbers/amounts/dates/names proofread.
- Original PDF/proofreading record kept.
Key facts
- 300dpi is usually enough.
- Skew/shadows reduce accuracy.
FAQ
Local or online tools for Scanned PDF?
Local Scanned PDF tools are more private and work offline; online tools save installation but files leave your device. A scanned PDF is images; OCR is required for search/copy.
How long does it take?
Usually 1-3 minutes; for intermittent issues, run 30 seconds and retest elsewhere.
Is data uploaded?
Runs locally and does not upload video/audio; extensions may still read the page.
Source: Adobe