Redact Scanned PDFs — Free Tool That Works on Image-Based Documents

Scanned PDFs are fundamentally different from native PDFs. A native PDF has a text layer — characters stored as data. A scanned PDF is a stack of photographs. Each page is an image. This means standard text-selection redaction tools do not work on scanned PDFs because there is no text layer to manipulate. The free redaction tool handles both types: it renders each page (whether text or image), lets you draw black boxes, and flattens everything into a new image. Scanned PDFs redact cleanly.

Why Scanned PDFs Need Different Treatment

When you scan a paper document on a flatbed scanner, copier, or phone camera, the result is a PDF where each page is a photograph of the paper. The "text" you see is actually pixels in an image — the PDF reader displays it, but it does not know the image contains words.

This means:

• You cannot select text in most scanned PDFs (unless OCR was run on them)
• Ctrl+F search does not work on the text content
• Text-based redaction tools that look for specific words to remove have nothing to find

The solution is visual redaction: draw black boxes over the areas containing sensitive information. Since the "text" is already just pixels, drawing black pixels over it is equivalent to destroying it — there is no separate text layer hiding underneath.

How to Redact a Scanned PDF

1. Upload the scanned PDF to the redaction tool
2. Navigate to each page using the page controls
3. Draw black rectangles over the sensitive content — names, numbers, addresses, signatures
4. Apply Redactions — the tool re-renders each page image with black boxes integrated
5. Download the redacted version

Because scanned PDFs are already images, the redaction process is even simpler conceptually: you are drawing black over parts of a picture. The tool ensures the black areas are permanently part of the image, not a removable layer.

Sell Custom Apparel — We Handle Printing & Free Shipping

What About Scanned PDFs With OCR?

Some scanned PDFs have been processed with OCR (Optical Character Recognition), which adds an invisible text layer on top of the page images. This makes the text selectable and searchable even though the page is still an image.

OCR'd scanned PDFs are the trickiest to redact because they have two layers of sensitive information:

• The visible image of the text on the page
• The invisible OCR text layer behind the image

The flattening approach handles both: when the tool flattens the page to a new image, both the visible image and the OCR text layer are destroyed and replaced with a fresh image that includes your black boxes. No text survives in either layer.

If you have OCR'd scanned documents, the WildandFree tool is actually safer than text-only redaction tools, which might remove the OCR text but leave the text visible in the page image.

Quality and File Size After Redacting Scanned PDFs

Redacting a scanned PDF re-renders each page image. This can affect quality and file size:

Quality: The tool renders pages at high resolution. For most scanned documents (300 DPI scans), the redacted result looks identical to the original. Very high-resolution scans (600+ DPI) may see slight quality reduction, but text remains fully readable.

File size: Redacted scanned PDFs are typically similar in size to the originals. The re-rendering may produce slightly larger or smaller files depending on the image compression. If the file is too large after redaction, run it through our PDF compressor.

Color: Color scanned documents stay in color. Black-and-white scanned documents stay black-and-white. The redaction process preserves the color mode of the original.

Frequently Asked Questions

Can you redact a scanned PDF?

Yes. The redaction tool draws permanent black boxes on the page images. Since scanned PDFs are images, this effectively destroys the content underneath — there is no hidden text layer.

Does OCR text get removed too?

Yes. The flattening process removes both the visible page image and any OCR text layer, replacing them with a new image that includes your redaction boxes. No text survives in any layer.

Will the redacted scanned PDF look blurry?

No. The tool renders at high resolution. For standard 300 DPI scans, the redacted result is visually identical to the original except for the black boxes.

Can I run OCR on a scanned PDF after redacting?

Yes. After redacting, you can run the result through an OCR tool to make the remaining text searchable. The redacted areas will be recognized as black boxes, not as text.