How to Blur Text in an Image (So Nobody Can Unblur It)

A screenshot about one thing always shows five others: an email in the corner, an API key in a terminal, a customer's name in a list. Here's how to hide them so they stay hidden.

Quick answer

Why a normal blur can be unblurred

A Gaussian blur spreads each letter over its neighbours, but it keeps all of them. Deblurring tools, plus a good guess at the font, can bring words back. That's why "unblur text" gets searched hundreds of times a month.

Pixelation isn't safer. Each block is the average of the pixels under it, and with small blocks the averages give the letters away. Depix, an open-source tool, recovers passwords from pixelated screenshots when it knows the font.

What a safe blur does

• Blocks bigger than letters. Average the area into patches a few letters wide, so no single letter is left to recover.
• A random nudge. Shift each patch by an amount nobody else knows, so the averages can't be matched against guesses.
• Painted into a new file. A box on a layer can be lifted off. A box painted into the pixels can't.
• No metadata. A phone photo carries where it was taken. Save a new file without it.

Any bar, tape or blur, still shows how long the hidden text was. For a password, draw it a little wider.

Blur text in an image with Statuz

Statuz does all of the above when you attach an image to a post, on the Mac app and on statuz.cloud:

1. Click the attached image.
2. Click a word to hide it, or drag across a few. Drag from an empty spot to box in a face or a logo.
3. Or take every email at once: Statuz reads the image and offers one button each for emails, phone numbers, links and keys.
4. Pick black tape, one of six colors, Blur or Glass. Every bar changes with it.
5. Click Done. The bars go into a new image that replaces the one you attached, without its metadata.

Play

Tape, blur or glass

Blur and glass in Statuz turn the text into patches of color before they soften it, so there's nothing to sharpen back.