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PDF Area Masking (Redaction)

No worries about OCR errors—drag directly over what you want to hide. Selected areas are permanently removed at the image level and cannot be recovered.

Beyond the limits of auto-detection: manual drag selection is the most reliable and precise way to hide exactly what you want—even in scanned documents or image files.
Your chosen style will be permanently merged into the output file and cannot be undone afterward.

Why is “area redaction” essential?

When sharing contracts, certificates, or financial reports, exposing personal data like ID numbers or bank account numbers is extremely risky. Simple pen-style coverups can be technically reversible, so professional redaction is required.

PDFNabi’s area redaction tool works without OCR: you visually select areas yourself, so there’s no risk of mis-detection. It works perfectly even on broken-text scans or image-based files.

The most important part is security. The moment you click “Apply masking & download,” the original data in the selected areas is completely deleted and replaced with new pixels. No one—using any tool—can reveal the hidden content again.

Why manual drag is safer than auto search

Auto text search can miss critical information when resolution is low or fonts are unusual. A security incident can happen from a single mistake.

Manual drag selection gives you 100% control over what you can see. If you want to eliminate system errors and hide content exactly as intended, manual selection is the most reliable approach.

  • Prevents leaks caused by recognition errors at the source
  • Can handle information hidden inside images or charts
  • WYSIWYG: review and confirm the final result before exporting

Recommended masking styles by use case

Choose the right masking method based on how the document will be used. It’s not only about deleting information—it also helps maintain a professional appearance.

Blackout is the most common, but for proposals or portfolios where design matters, blur or mosaic can look more natural.

  • Black (Blackout): the standard approach for contracts or official documents with legal requirements.
  • White (Whiteout): useful when you want it to look like the content was never there.
  • Mosaic/Blur: recommended when you need to naturally hide parts of an image, like faces in photos.

Frequently asked questions (FAQ)

Can I remove the masking or undo it later?+

No. That’s the core of Redaction. It doesn’t just paint over content—it destroys and merges the underlying data permanently, so a downloaded file can never be restored to the original.

Does it work for PDFs made from smartphone photos?+

Yes. This tool doesn’t rely on text recognition—it works based on on-screen positions—so photos, scans, and even handwritten notes can be masked reliably.

Can I mask information across multiple pages at once?+

In the current version, we recommend reviewing each page visually for maximum accuracy. If you uploaded multiple files, you can select them one by one, work carefully, and save each file separately.