Redact PDF Content

Redaction removes content from the page: the matched text, and optionally the image and vector content underneath it, is deleted from the content stream and the area is painted over. Drawing a black rectangle on top of text is not redaction, because the text stays extractable.

OfficeIMO.Pdf redacts in three steps: search builds a reviewable plan, apply removes the planned content, and verification checks the saved bytes for anything that is still extractable.

Redact text by literal or pattern

C#

using OfficeIMO.Pdf;

PdfDocument source = PdfDocument.Load("statement.pdf");

PdfRedactionPlan plan = source.Redactions.Search(new PdfRedactionSearchOptions {
    TextSelection = PdfRedactionTextSelection.MatchedGlyphs,
    ContentScope = PdfRedactionContentScope.TextOnly
}.AddLiteral("Contoso Ltd").AddRegex(@"\b\d{3}-\d{2}-\d{4}\b"));

Console.WriteLine($"{plan.Matches.Count} matches, reviewable: {plan.IsReviewable}");

PdfRedactionApplyResult result = source.Redactions.ApplyWithEvidence(plan).ThrowIfUnverified();
result.ToDocument().Save("statement-redacted.pdf");

ThrowIfUnverified throws when the evidence reports residual or inconclusive matches, so an unverified file is never saved by accident. MatchedGlyphs removes only the matched characters; the default removes the whole text block that contains a match.

PowerShell

Get-OfficePdfRedactionPlan -Path .\Contracts\MSA-Contoso.pdf -Pattern 'Account: \d+'
Remove-OfficePdfContent -Path .\Contracts\MSA-Contoso.pdf -OutputPath .\Contracts\MSA-Redacted.pdf -Text 'Contoso Ltd'

CLI

The CLI separates planning, reviewed decisions, and application, and writes JSON evidence for each step:

officeimo pdf redact plan contract.pdf --recipe redaction.recipe.json --evidence contract.plan.json
officeimo pdf redact apply contract.pdf --recipe redaction.recipe.json --decisions contract.decisions.json --output contract-redacted.pdf --evidence contract-redacted.evidence.json
officeimo pdf redact verify contract.pdf --recipe redaction.recipe.json --decisions contract.decisions.json --output contract-redacted.pdf --evidence contract-verify.evidence.json

The recipe and decision file formats are described in PDF workflows in the CLI.

Limit the search

Restrict the search to specific pages, form fields, or case-sensitive matches:

using OfficeIMO.Pdf;

var options = new PdfRedactionSearchOptions { MatchCase = true }.AddLiteral("Internal only");
options.PageNumbers.Add(1);
options.PageNumbers.Add(2);

PdfRedactionPlan plan = PdfDocument.Load("memo.pdf").Redactions.Search(options);

Limits and reference

Limits: scanned pages need a text layer (OCR) before text can be found. See the PDF package row.

Reference: OfficeIMO.Pdf API · Remove-OfficePdfContent