Guide

Is blurring text in a screenshot safe?

Short answer: not reliably. Blur and fine pixelation hide text from your eyes, but software can sometimes work out what was underneath. Here’s why, and what to do instead.

Why blur can be undone

Blurring doesn’t delete information; it smears it. Each blurred pixel is a predictable mix of the pixels around it. If someone can guess the font and size, which on a screenshot is usually easy, they can blur candidate text the same way and see which guess matches. Phone numbers, card numbers and short codes are especially vulnerable because there are only so many possibilities.

Pixelation has the same problem

Pixelation replaces areas with flat blocks of their average color. With small blocks over text, researchers have shown it can be reversed: tools like Depix and Bishop Fox’s Unredacter reconstructed pixelated text by testing likely characters until the blocks matched. Large blocks that cover a whole line in one or two rows leave far less to work with.

The highlighter trap

Drawing over text with a marker or highlighter often leaves it slightly see-through. Brightening or adjusting the levels of the image can make the text readable again. Always use a fully opaque shape.

What’s actually safe

Solid black (or any opaque) bars that fully cover the text, with a little margin.
A new image. Export or save a flattened copy, so there’s no editable layer underneath.
Very coarse pixelation, if you prefer the look: blocks as tall as the text, so each line becomes one or two rows of color.
Hide the context too. A name can often be guessed from the profile photo or the first letters next to it.

How Scrubshot does it

Scrubshot never uses blur. It burns solid bars, or pixelation with blocks half the height of a line, into a brand-new image, so there’s nothing underneath to recover and no hidden metadata comes along.