Lesson 17 of 24
How to blur a face, a logo or a number plate in a video
Blur a face in video, or a logo, a number plate or a password, with a cover that follows it as it moves, and check nothing slips through, on your Mac.
hopeengineer · Founder of Sharpy and Threadify18 October 2026 · 7 min read
The short answer
To blur a face in a video, cover it on every frame it appears in, with a cover that follows the face as it moves, then watch the result to be sure nothing slipped through. Sharpy covers a face, a logo, a name on a screen or a number plate for the whole edit and follows it, checks the cover with a second detector that was not told where to look, and reports a track it loses instead of guessing. In screen recordings, keys, tokens, card numbers and passwords are blurred automatically. Nothing leaves your Mac.
When should you blur a face in a video?
Blur when someone who appears has not agreed to be in it, or when showing them could harm them. The usual cases:
| What | Why it is often blurred |
|---|---|
| Passers-by in a vlog | They did not agree to appear |
| Children who are not yours | Their parents did not agree, and children are more at risk |
| People in a sensitive setting | A clinic, a protest, a support group, a workplace |
| Number plates | They can lead back to a person and an address |
| House numbers and street signs | They locate someone's home |
| Screens and papers | Names, emails, messages and account details |
| Logos and brands | A sponsor's rival, a brand that has not agreed, a deal that needs it |
The law differs from country to country, and this is not legal advice. In the UK, the data protection regulator, the ICO, defines personal data as information about someone who can be identified, directly or indirectly. Platforms have their own rules too. YouTube's privacy guidelines let a person ask for a video to be removed when they are uniquely identifiable in it, through a combination of image, voice, full name and other details; a fleeting image would not likely qualify. When YouTube receives such a complaint, it may give the creator time to remove or edit the private information first.
When in doubt, ask for consent, or blur.
How do you blur a face in a video?
Whatever tool you use, the job has four parts:
- Find every appearance. A face that is covered in one shot and bare in the next is not hidden.
- Cover it fully. Make the cover larger than the face, and strong enough that the face cannot be made out. A light blur on a large face can still be recognised.
- Follow it. People move, cameras move. The cover has to stay on the face, frame after frame.
- Check the result. Watch the finished file, not the timeline, at full size, paying attention to the first and last frames of each appearance.
Remember the other ways to recognise someone: a voice, a name said aloud, a tattoo, a car, a uniform with a name on it. Covering a face alone may not be enough.
How do you blur a moving object in a video?
Track it. A tracker follows the face, the plate or the logo through the shot and moves the cover with it. Trackers can drift onto the wrong thing, so the follow is what to check most carefully.
Sharpy follows a face with its face detector and anything else, a logo, a name on a screen or a number plate, by its appearance. The difference matters. On a 98-second test take, a simple tracker that follows a patch of picture reported "followed for 98.0 s" while it sat on the door frame: its cover was on the face in 0 of 176 samples. Following the face detector, Sharpy's cover was on the face in 176 of 178 samples.
When a tracked thing leaves and never comes back, Sharpy reports the track as lost rather than following something else. Its tracking pins text, graphics, blurs and effects to anything in a shot, including a person whose face is not visible, and says the moment it loses a point instead of carrying on blind.
How do you hide a face, a logo or a number plate in Sharpy?
- For the whole edit. When Sharpy assembles a piece, ask it to hide the face of whoever is on camera, and it covers them for the whole edit. A standing rule can remember who to hide, so you do not ask every time.
- For one thing, for a stretch. Give the command line a box around what to hide, when it starts and for how long, for example
sharpy hide in.mp4 --box 0.59,0.25,0.19,0.39 --from 12 --seconds 8, and the cover follows it from there. - By hand in the window. Lay a copy of the clip on the track above, give the copy a blur from the effects shelf, and drag out a box or oval mask on the picture so only the blurred part over the face shows. Move, size and soften the mask in place, and let it track the face. The window shades what a mask hides and labels it "covers" or "keeps".
Then Sharpy checks its own work. The cover is checked by a detector that was not told where to look, and the finished file is expected to have no readable face in it. If a cover cannot be made, Sharpy says so and why, rather than shipping the face uncovered. Still watch the finished file yourself: 176 of 178 is close, not perfect, and you are the one publishing it.
How do you blur passwords in a screen recording?
Screen recordings leak more than faces: an API key in a terminal, an email address in a sidebar, a card number on a checkout page. Sharpy blurs API keys, tokens, emails, card numbers and password fields on every frame they appear on, following scroll and zoom, down to a single word of a secret.
It also keeps less in the first place. Nothing at all is kept while a password field has focus, and plain typing is stored only as timing. Shortcuts show on screen by default, and showing single keys or all typing is a choice you make per recording. How to screen record on a Mac covers the rest of the recorder.
Can you blur faces after uploading to YouTube?
Yes. YouTube Studio's editor on a computer has a Blur option with two kinds. Face blur finds faces and lets you pick which to blur; custom blur covers any area you draw. A custom blur can track the object or stay in a fixed position. YouTube notes that for unedited videos with over 100,000 views you may be unable to save changes other than face blurs, unless the channel is in the YouTube Partner Program.
Blurring before you publish is still safer: the original is never public, and you choose the strength of the cover. Because Sharpy runs on your Mac, the unblurred footage never leaves it, which matters most for exactly the footage you are blurring. Edit video with AI without uploading your footage explains why that matters.
Before this lesson: how to put text behind a person. Every lesson is in Learn Sharpy.
Frequently asked questions
01How do I blur someone's face in a video?
Cover the face on every frame it appears in, with a tracker so the cover follows it, then check the finished file. In Sharpy, ask it to hide the face and it follows the face for the whole edit and checks the result.
02How do you blur a moving object in a video?
Track it and attach the blur to the track. Check the track by eye, because trackers can drift onto the background.
03Is it illegal to post a video with someone's face without consent?
It depends on the country, the setting and what the video is for, so check the rules where you live. Platforms such as YouTube also let identifiable people ask for removal.
04Does blurring a face make a person anonymous?
Not always. A voice, a name, a car or a place can identify someone, so consider muting, bleeping or cutting those too.
05Can I blur a number plate in a video?
Yes. Sharpy follows a number plate by its appearance and keeps the cover on it while it moves.
Sources
Checked on 18 October 2026.
Written by
hopeengineer
Software architect and founder of Sharpy and Threadify. Builds scalable systems and AI tools, and writes here about how Sharpy understands and edits video.
Sharpy opens on 1 November 2026.
The world's first context-aware agentic video editor, on your Mac. One plan, unlimited edits.