How to redact a scanned PDF
A scanned PDF is a picture of each page, so there's no text to select. You don't need OCR to redact it: covering each detail with a box works. The one trap is a scan that has been through OCR and carries hidden text.
Open the redaction tool Free, no account. The file stays on your device.Quick steps
- Open maskyourdocs and choose the scanned PDF.
- Draw box is already selected. Drag over each detail to hide.
- Go through every page, zooming in on small print.
- Press Export, then Generate, then Download.
Two kinds of scanned PDF
- Image only. Each page is a picture. You can't select or search anything.
- Scanned with OCR. Text recognition has placed an invisible layer of text over the picture, so the file can be searched. A box drawn over the picture in an ordinary PDF editor leaves that invisible text behind.
To tell which you have, try searching the PDF for a word you can see. maskyourdocs also tells you when the file opens: if it says This PDF is a scan with no text layer, it's image only. If Find text works, the scan has a text layer, and you can use it to find every copy of a name. Every page you mark is flattened to an image on export, so the hidden text on those pages goes too.
Step by step
Step 1: Open the scan
Go to maskyourdocs, press Choose a file and pick the PDF. For an image-only scan, Draw box is the only tool, and search is switched off.
Step 2: Cover each detail
Drag a box over each name, number, signature, stamp or photo. On a phone or tablet, rest a finger on the spot until a ring appears, then drag. A quick swipe still scrolls, and two fingers pinch to zoom. Zoom in on small print, and cover a little more than the text: scans are often slightly tilted.
Step 3: Go page by page
On an image-only scan nothing can be searched, so every copy of a name has to be found by eye. Work through each page in order, including the back pages and any attachments.
Step 4: Choose the export quality
Press Export and choose a resolution: Screen: 150 DPI for the smallest file, Standard: 200 DPI for most documents, or Print: 300 DPI for small print you need to stay sharp.
Step 5: Generate and check
Press Generate, then Download. Open the result and look at every page once more.
What the automatic check can and can't do
After export the tool confirms that no text is left on the pages you marked, which is what catches a hidden OCR layer. On an image-only scan there's no text for it to read, so it can't confirm what's under your boxes. That part is up to your eyes: zoom in on the result and check every box covers its detail completely.
Documents that are partly scanned
Some PDFs mix typed pages with scanned ones, such as a contract with a signed, scanned last page. Find text works on the typed pages; use Draw box on the scanned ones.
Questions
Do I need OCR to redact a scanned PDF?
No. Draw a box over each detail. OCR only matters if a scan already has an OCR text layer, in which case the page needs flattening, which maskyourdocs does for every page you mark.
Why can I search my scanned PDF?
It has been through OCR, which adds an invisible text layer. That text has to be removed too, not just covered.
Will the redacted scan be blurry?
Choose Standard (200 DPI) for most documents, or Print (300 DPI) for small print. Higher settings make larger files.
Can I redact a photo of a document instead of a PDF?
Yes. Open the JPEG, PNG or HEIC photo and draw boxes the same way.