Blur an image

Hiding part of a photo

Choose Selected areas and drag a box over each thing you want hidden: a face in a crowd, a car’s number plate, a house number, the name on a parcel label. You can mark as many areas as you like, and remove one with its × button. Only those boxes are changed; the rest of the photo stays sharp.

Blur or pixelate: which hides better?

For anything that must stay secret, such as text, numbers or a face that could be recognised, use Pixelate with large blocks or a strong blur. A light blur on short text can sometimes be guessed, because each letter leaves a characteristic smudge. The rule of thumb is that the blocks or blur radius should be larger than the letters themselves.

Because the tool saves a brand-new image built from pixels, the original detail under the blurred area is not hidden in the file somewhere. It is gone. That is not true of every app: some PDF editors and phone markup tools only lay a shape over the top, which can be removed later.

The five blur styles

• Stack (default): fast, smooth, close to Gaussian. A good general choice.
• Gaussian: the classic soft blur used in photo editors, approximated with three box passes.
• Box: a slightly harder-edged blur; 1 to 3 passes.
• Motion: smears along an angle from 0° to 180°, like a camera moving. Useful for a sense of speed rather than privacy.
• Pixelate: replaces the area with flat squares of 2 to 64 px. The most reliable way to make text unreadable.

Blurring the whole image

Whole image softens everything, which is handy for slide and website backgrounds where text needs to sit on top of a photo, or for a frosted-glass look. A radius of 20 to 40 px usually turns a busy photo into a calm wash of colour.

Want the opposite, a photo that is a little too soft? Try Sharpen image.

Questions