OneTaskBy Tim King · Updated
Blur Video Region
Hide a Number Plate or Screen in a Video With Blur or Pixelation
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How the Blur Video Region works
Blur video areas before you share a clip: a number plate, a phone screen, a house number or a whiteboard. Set the rectangle as percentages of the frame, choose blur, pixelate or a solid black box, press Render and download. Your file is processed in the browser and never uploaded.
Posting a clip often means posting more than you meant to. Dashcam footage shows other drivers' plates. A screen recording catches a notification. A walk-through video of a flat shows the address on the door. Cropping removes too much, so the usual fix is to hide one fixed area for the whole clip.
How to blur video areas here
Positions are given as percentages of the frame, so the same numbers work on any resolution. Left 0 and Top 0 is the top-left corner. Left 50 is the middle. Width and Height set the size of the box. The area is clipped to the frame, so a box that would run off the edge simply stops there.
| Area to hide | Left | Top | Width | Height |
|---|---|---|---|---|
| Bottom-right corner logo | 80 | 85 | 18 | 12 |
| Lower third caption bar | 0 | 75 | 100 | 20 |
| Top status bar on a phone recording | 0 | 0 | 100 | 6 |
| Centre of the frame | 35 | 35 | 30 | 30 |
| Left half | 0 | 0 | 50 | 100 |
Pause the preview player on the frame where the object is largest, estimate its position, and render a short test with the video trimmer if the clip is long.
Blur, pixelate or black box?
Blur shrinks the area to about one twelfth of its size and scales it back up with smoothing. It looks soft and natural and suits faces in the background or a cluttered desk.
Pixelate shrinks the area to blocks of about 16 pixels and scales it back without smoothing, the classic mosaic look. It reads clearly as deliberate censoring.
Black box fills the area with solid black. This is the only option that destroys the content completely, and it is the right choice for anything sensitive.
A warning about blur and pixelation
Light blur and large-block pixelation are not secure. Researchers have recovered text and numbers from pixelated images by trying candidate strings, pixelating them the same way and comparing. Video makes it easier, because the same area is captured dozens of times a second with slight movement. For passwords, card numbers, ID documents and anything legally sensitive, use Black box.
Tips and pitfalls
Moving objects: the box is fixed for the whole clip. If the object moves, make the box large enough to cover its whole path, or trim the clip into sections and process each one.
Make the box generous. Add a few percent on each side. Slight camera shake or a re-encode can otherwise leave an edge of the hidden content showing on some frames.
Audio is kept. The original soundtrack is recorded with the picture. If someone reads a number aloud, mute the video as well.
How to read the result
The stats give the hidden area in pixels with its top-left position, the share of the frame it covers and the file size. Scrub through the result to check the area stays covered, then Download.
FAQ
Can blurred or pixelated video be reversed?
Not exactly, but text and numbers can sometimes be guessed by matching pixelated candidates, and video gives an attacker many frames to work with. Treat blur and pixelation as cosmetic. Use the Black box effect for anything that must be truly unreadable.
Can the blur follow a moving face or object?
No. The area stays in the same place for the whole clip. Cover the full path the object takes, or split the clip with the video trimmer and blur each part with its own position and size.
Is my video uploaded to blur it?
No. Every frame is drawn and recorded by your own browser. The video never leaves your device, which matters when the whole reason for blurring is that the footage contains private information.
Why are positions in percent and not pixels?
Percentages work on any resolution, so the same numbers fit a 4K original and a 720p copy. The stats after rendering show the exact pixel rectangle that was hidden, if you need to note it.
See also: all Video & Screen tools, Images, Audio, PDF, SVG, Simulations & Screensavers, Generative Art, Chart Makers, 3D Model Viewers, Drawing Pads, Mockups & 3D Making, Diagram Makers, 3D Science, Tracker Music.
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