Hide a License Plate or Face in a Photo
Why blur isn't enough, and what to use instead.
The Short Answer
Cover the plate with a solid box, not blur. Blur and pixelation don't delete the characters; they average them. For short text in a known font, like a plate number, that average can be enough to work out what was there.
A solid box leaves nothing to work out. Then save the result as a new file, so the photo's hidden location data doesn't go along with it.
Black out a plate or face →How to Do It
- Open the Photo Redactor and choose the photo. It opens in your browser and is not uploaded.
- Drag a box over the plate. Make it a little bigger than the plate, so no edge of a character shows.
- Drag more boxes over anything else that identifies someone: faces, house numbers, street signs, other cars.
- Leave each box on Solid black. Only switch to Pixelate for things like a face in a crowd, never for text.
- Choose PNG or JPG and tap Download. The new file contains only the edited pixels; GPS location, camera model and date are left behind.
- Share the new file, and keep the original private.
Why Blur Isn't Enough
Blur spreads each pixel into its neighbours. Pixelation replaces each block with its average colour. Both keep a summary of what was there, and a summary of a few characters from a known font can be matched.
- Research on text. In 2016, researchers at UC San Diego used statistical models to recover pixelated and blurred text from screenshots, including real-world examples, and concluded that both methods "are not viable approaches for text redaction" (PETS 2016 paper).
- A public tool. Depix is an open-source proof of concept that recovers text from pixelated screenshots. Its author built it after someone pixelated part of a password. It needs the same font and editor to compare against, so it doesn't work on everything.
- Research on faces. A 2016 study from Cornell Tech and the University of Texas at Austin trained a neural network on a set of 40 people. It identified people in YouTube-style blurred faces 57% of the time, against 2.5% by guessing, even though the authors couldn't recognise those faces themselves (paper on arXiv).
None of this means every blurred plate can be read. It means you can't tell by looking whether yours can. A solid box removes the question.
Things That Trip People Up
- A box that's too small. The tops of letters or the plate's edge sticking out can be enough to narrow it down. Go bigger than you think.
- Highlighters. Highlighter tools in markup apps are see-through by design. Use a solid shape.
- The same thing twice. A plate can also show in a reflection, in a second photo from the same set, or on the front of the car when you only covered the back.
- Location data. A photo can store where it was taken. Hiding the house number doesn't help if the file says where the house is.
- Old image data left in the file. In 2023, a bug nicknamed aCropalypse meant images cropped or marked up with Google Pixel's Markup tool and the Windows Snipping Tool could keep part of the original picture at the end of the file (report). Both were fixed, but it's why saving a completely new file is the safer habit.
On iPhone, Android and Computers
iPhone: open the redactor in Safari and choose the photo from your library. If a HEIC photo won't open in another browser, use Safari or convert it with HEIC to JPG first.
Android: open the redactor in Chrome and pick the photo from the gallery. Draw boxes with your finger.
Windows and Mac: any current browser works. Drag with the mouse.
The redactor works on still photos and screenshots, not video.
Frequently Asked Questions
Is blurring a license plate enough?
Not always. Blur and pixelation average the pixels rather than removing them. Plates use a small set of characters in a known font, which is exactly the situation where research and tools have recovered or guessed hidden text. A solid box removes the information completely, so it is the safer choice.
Can blurred or pixelated text be unblurred?
Sometimes. A 2016 study from UC San Diego recovered pixelated and blurred text in screenshots and concluded that neither is a viable way to redact text. The open-source Depix proof of concept recovers text from pixelated screenshots when the font and editor can be matched. It does not work on every image, but you cannot know in advance that yours is safe.
What is the safest way to hide a face in a photo?
Cover it with a solid shape that is a little larger than the face, then save the photo as a new file. Blurred faces are much harder to reverse than text, but a 2016 study showed a neural network could still tell people apart in YouTube-style blurred faces far more often than chance.
Does hiding the plate remove the location from the photo?
Not by itself. Phone photos often store GPS location in their EXIF data. The Fair Toolbox Photo Redactor saves a new image drawn from the edited pixels, so that data is not carried over. Other editors may keep it.
Do I have to hide license plates before posting photos?
Rules differ by country and platform, so check the rules where you live and on the site you are posting to. Many people hide plates anyway because a plate can link a car, and its owner, to a place and time.
Can someone remove a black box from a photo?
Not if the box was drawn into the pixels and the image was saved as a new file, because nothing of the original remains under it. Problems happen when an app keeps the original underneath, as with editable layers, or leaves old image data in the file.