Blur Image Online: Whole Picture or Just One Area

How do I blur an image?

Choose a picture and the whole image appears blurred. Drag the Blur strength slider until it looks right, press Apply, then press Save picture. The saved file is a new image at full resolution and your original stays untouched. To blur only part of the picture, switch the area to Drag a box or Brush.

1. Press Choose a picture, drop a file, paste with Ctrl+V, or press Take a photo on a phone.
2. The picture shows blurred right away. Drag Blur strength to change the radius.
3. For one area only, pick Drag a box or Brush and mark the part to blur.
4. Press Apply to keep the blur. Each Apply is one undo step.
5. Open Export for the format, then press Save picture and download the file.

For a blocky look rather than a smooth one, see Pixelate Image. To crop away the part you do not need, use Crop Image.

How do I blur a face or censor part of a photo?

Switch the area to Drag a box, drag over the face, license plate or other detail, and the blur appears there at once. Use Brush for shapes a box misses, then press Apply. You can mark several areas before Apply, and Remove last area takes one away.

The blur reads the picture around a box too, so the edge of the box blends into its surroundings instead of showing a hard rectangle. Raise the strength until the detail is gone, then zoom in on the preview to check.

Can I blur only the background of a photo?

Yes. Blur Background finds the subject with an AI model on your device and blurs the rest in one step. To do it by hand here, switch to Brush, raise the brush size and paint over the background while the Blur effect is on. The subject stays sharp, and Remove last area fixes a stray stroke.

For the automatic version, open Blur Background. By hand, a large brush covers wide areas quickly, and a small brush cleans up the outline; the blur follows exactly the strokes you draw.

How strong should the blur be?

The slider shows the blur radius in pixels on the saved picture. The setting scales with the picture, so one slider position looks alike on a phone photo and on a camera photo. Pick a radius that hides the detail you care about, then zoom in on the preview to check.

The radius is the standard deviation of the Gaussian, in pixels. Doubling it doubles how far detail spreads.

What kind of blur does the editor use?

It uses a Gaussian blur, built from three passes of a box blur, which is a standard way to approximate one quickly. Pixels at the edge of the picture repeat outward, so the borders do not darken. A box reads the area around it, so its edge blends in.

The ramp width grows in step with the radius, which is how a Gaussian behaves. The Wikipedia article on Gaussian blur describes the filter and the box blur approximation.

Is a blurred image safe for hiding private information?

A strong blur hides a great deal, but a weak one can sometimes be sharpened or guessed, especially for text and faces. For anything that must stay private, use the Redact box, which paints a solid color and keeps nothing of the old pixels. The editor never uploads your picture.

A small pixel size or a weak blur can sometimes be guessed or partly reversed, especially for text and faces. The Redact box paints one solid color and keeps nothing of the old pixels, so it is the safer choice for passwords, account numbers and anything private.