How to redact a scanned PDF

A scanned page is usually a picture. Searching its PDF text layer may find nothing even when an identifier is plainly visible. Treat it as an image until you have checked what text is actually present.

Check scan quality first

Look for blur, faint print, skew, clipped edges and small characters. If you control scanning, improve the source rather than relying on recognition to repair it. Test multiple page types, including a page with an image below a selectable header.

Distinguish recognition from removal

OCR estimates the characters shown in the image. A searchable-PDF tool adds recognized text to make search and copying possible; it does not remove the original visible information. CloakDoc’s Make PDF searchable utility should not be treated as a redaction step.

Use the batch identifier workflow

CloakDoc checks native text and rendered printed English content for selected identifier patterns. It uses locally supplied OCR assets. When a match is found, the batch export covers that region in the page image and reconstructs the PDF without the original text layer.

The current English recognition workflow is not a promise of reliable handwriting or multilingual recognition. Page rendering also bounds resolution to manage memory. Very small text may be missed even when the overall page looks readable.

Compare source and output

Review each intended removal at a useful zoom. Check other occurrences of the same value. Recognition mistakes such as confusing 1, I and l can prevent a rule from matching. Also inspect names, signatures and visual identifiers that are outside the rules.

Preserve the right result

Save the reviewed redacted copy separately from both the source scan and any searchable OCR copy. Do not distribute the searchable original alongside the redacted file. Use a different workflow when the required region is not covered by supported identifier detection.