Can blurred or pixelated text be unblurred?

Yes, sometimes

Blur and pixelation don't delete information; they average it. Each blurred pixel is a mix of the pixels around it. If an attacker can guess what the original could have been, they can try every candidate, blur it the same way, and see which one matches.

This is not theoretical. Researchers have published open-source tools, such as Depix, that recover pixelated text from screenshots, and in 2007 investigators reversed a digital swirl that a suspect had used to disguise his face in photos.

What makes text easy to recover

• Few possibilities: digits, PINs, OTPs, card and account numbers. Ten options per character is a small search.
• A known font: screenshots of apps and websites use standard fonts at standard sizes, which makes candidates easy to render.
• Light blur or small pixel blocks: more of the original survives.
• Clean, uncompressed images: a PNG screenshot keeps the exact averages an attacker needs.

Long paragraphs of free text, heavy blur and large pixel blocks are much harder to reverse, and faces with strong blur are generally safe.

The reliable option: a solid box

A solid box replaces the pixels completely, so there is nothing left to average or match. For numbers and short text, it's the only choice that can't be reversed.

In Blur Document, Censor screenshot and Black out text in PDF start with solid boxes, and the editor warns you whenever blur or pixelation covers text.

Rule of thumb: blur faces and photos, black out numbers and text.

Don't forget the file itself

Even a perfect box fails if it's only a layer on top. In PDFs and some image editors, the original text or image can still be inside the file. Export to a fresh file whose pixels contain the box, which Blur Document always does.