Example post: How OCR changes what 'redacted' means
[Example content] A huge share of the documents that need redaction aren't native text at all — they're scans, photos of paper forms, or PDFs generated from an image. Without OCR, none of that content is even visible to an automated detector.
Text that isn't text
A scanned page looks the same as a native PDF page to a human reader, but to software it's just a grid of pixels until something extracts the text layer. Skip that step and a detector has nothing to search.
Where accuracy actually matters
OCR accuracy on a clean, high-resolution scan is a solved problem. The harder cases are the ones real-world documents actually produce: skewed pages, low-contrast copies, handwriting mixed with print, and multi-column layouts.
This is why treating OCR as a preprocessing checkbox undersells it — the quality of that step sets a ceiling on what the redaction step downstream can possibly catch.