How to blur faces in a photo before you post it

The photo from the school trip is lovely, but not every parent agreed to their child being on the class page. The street shot is great, except for the stranger looking straight into the lens. The picture of the dent in your car shows the other driver's number plate. Blurring the parts that are not yours to share takes a minute, and doing it properly takes about the same.

Why bother

A recognisable face is personal data. Posting someone's photo publicly generally needs their consent, and with children that goes double: it is their parents who get to decide, and the photo stays online far longer than the moment it captured. Blurring is the simple way to share the moment without dragging everyone in it along.

The same goes for details that identify people indirectly:

• number plates,
• house numbers and addresses on envelopes or parcels,
• names on badges, lanyards and name tags,
• screens and documents in the background,
• school logos on uniforms, when combined with a face or a first name.

A weak blur is not a blur

The most common mistake is a gentle blur that looks fine to you, because you know who is under it. Mild blurring keeps the shape, the hair and the colouring, and people who know the person can often still tell who it is. A weak blur can sometimes be partly reversed, and a pixelated face with large enough squares can still be matched against other photos.

So when someone really must not be recognised:

• push the strength high enough that you cannot tell who it is either,
• use a coarse mosaic rather than a soft blur,
• or cover the area completely with a solid block.

For number plates and text, a solid block is the safest option.

Blur that stays blurred

There is a second trap. A blur sticker in a phone app, a shape drawn over a face in a presentation or a black rectangle in a PDF can often be removed afterwards, because the original picture is still underneath. The person you send it to can simply move the sticker.

In Blur faces the blurred pixels are written into the picture itself. The downloaded file does not contain the original face at all, so there is nothing to uncover.

How to do it

1. Open Blur faces and drop in the photo.
2. Mark the areas. Tapping creates an area of a sensible size, which is quick for faces. Dragging draws it exactly, say a thin strip over a number plate. Tap inside an area to remove it.
3. Choose the shape. An oval suits faces, a rectangle suits plates, documents and text.
4. Let it find faces for you where your browser supports it. Chrome on Android and some other browsers have built-in face detection, and the Find faces button uses it. Always check the result yourself: profiles and partly covered faces often slip past the detector.
5. Set the strength, check the preview and download.

The whole edit runs in your browser. The photo never leaves your computer, which you can confirm by switching off Wi-Fi and seeing that it still works.

What else a photo gives away

Faces are the obvious part. The less obvious one is the file itself. Photos from a phone usually carry EXIF data, including the GPS position where the picture was taken. Posting a photo taken in your garden can hand out your home address.

The picture saved by the blur tool is drawn fresh, so no EXIF data comes across, GPS included. The original file on your phone still has it, so share the edited version, not the original.

When you want the opposite

Sometimes the goal is not to hide one person but to make one person stand out. Blur background keeps the subject sharp and softens everything behind it, like portrait mode on a phone. It is a good fit for a profile picture taken somewhere busy.

And for anything more involved, like removing a whole object or cloning over a sign, open the photo in the Image editor, which has layers, selections and brushes.

Frequently asked questions

Is the photo uploaded anywhere?

No. The editing runs entirely in your browser and the photo never leaves your device.

Can a blurred face be recovered?

Not from the file you download, because the blurred pixels replace the original ones. A light blur can still leave a face recognisable to people who know the person, though, so use a strong blur, a coarse mosaic or a solid block when it matters.

Does the location data stay in the photo?

Not in the edited picture. It is redrawn from scratch, so EXIF data including GPS coordinates is not carried across. The original file keeps it.

Can I blur several faces at once?

Yes. Mark as many areas as you need; the undo button removes the last one.

What format is the result saved in?

You choose when downloading. A photo that came in as JPEG is offered as JPEG first, anything else as PNG, and WebP is available too.