How to blur faces and number plates in a photo properly

A photo of a street, a school event, a car accident or an office party almost always includes someone who did not ask to be in it. Before it goes online, the people and details that do not belong there should be hidden — and hidden in a way that cannot be undone.

What to hide

• Faces of people who have not agreed to be shown, especially children.
• Vehicle number plates.
• House numbers, street signs and anything else that pins down an address.
• Name badges, ID cards and uniforms with names.
• Screens and documents in the background — monitors, phones, letters on a desk.

Blur a photo step by step

1. Open Blur Faces in a Photo and add the picture.
2. Drag a box across each face, plate or detail that must be hidden.
3. Raise the blur strength until nothing in the boxes is recognisable.
4. Apply, then download the result.

You mark the areas yourself; nothing in the photo is analysed and no face data is created. The photo never leaves your device, which is rather the point when it shows people who want privacy.

Why blurring here is permanent

Each marked area is redrawn from the original pixels through a blur, and the blurred result becomes part of the saved picture. The detail inside it is destroyed, not covered.

That is different from drawing a black rectangle over a photo inside a document, a slide or a PDF editor. There the shape usually sits on top of the untouched picture, and anyone who moves the shape — or extracts the image — sees everything. If a photo will be placed in a document, blur it first and insert the blurred file.

How strong is strong enough?

A light blur is not always safe. Faces can still be recognised by someone who knows the person, and a weakly blurred number plate or line of text can sometimes be guessed, because there are only so many possible combinations. Use a strong blur, then check the result at full size: if you can make out any feature, apply it again more strongly. When in doubt, go further.

The details people miss

• Reflections in windows, mirrors, car paintwork and sunglasses.
• Partial faces at the edge of the frame or behind other people.
• Hair, ears and clothing. A blurred face above a distinctive jacket is still recognisable to anyone who knows the person — extend the box.
• Text on screens that is small in a thumbnail but readable at full size.

Sometimes cropping is better

If the person or detail is near the edge, cutting it out entirely with Crop Image leaves a cleaner picture than a blurred patch. Blur what you cannot crop.

Remove the hidden data too

A photo can carry the exact GPS location where it was taken, inside the file. Blurring a house number achieves little if the file states the address's coordinates. Run the final picture through the EXIF Viewer and Remover before posting — see how to remove location data from photos.

Ask when you can

Blurring is the fallback. For photos of identifiable people — colleagues, other people's children, customers — the best practice is to ask before posting, and many schools, workplaces and events have their own rules. The law on publishing images of people varies between countries; blurring is a sensible precaution, not a substitute for following the rules that apply to you.