Pixelate & Blur Image

What the brush actually paints

When your image loads, two hidden copies of it are prepared straight away. One is a pixelated version, built by shrinking the picture down by the strength factor and drawing it back up to full size with image smoothing switched off, which is what produces hard square blocks rather than a soft ramp. The other is a blurred version, produced by redrawing the picture through a canvas blur filter set to the same number of pixels. Painting with the brush clips a circle at your cursor and stamps the matching copy through that circle onto the visible canvas. Nothing is masked or layered, so the pixels underneath are genuinely replaced, and the detail cannot be pulled back out of the file you download.

Jobs this handles every day

• Hiding a number plate before a car goes up on Facebook Marketplace, Gumtree or Carsales.
• Covering a street number and letterbox in real estate or rental listing photos.
• Blocking out a bank account number, BSB or customer reference in a screenshot you are sending to support.
• Obscuring the faces of children whose parents did not return a photo consent form before a school newsletter goes out.
• Censoring names and email addresses in a screenshot of a mailbox or a chat thread used in documentation.
• Removing a signature or a Medicare number from a scanned form before it is shared internally.
• Producing a deliberately blocky privacy effect on a background bystander in a travel photo.

Controls, defaults and the whole image mode

Strength runs from 4 to 60 and starts at 12. It is a single slider feeding both effects: in pixelate mode it sets the block size in source pixels, and in blur mode it sets the blur radius. Brush size runs from 10 to 200 and starts at 50, measured in screen pixels and then converted to source pixels, so the circle you paint is the same size you see regardless of how far the image is scaled down to fit your window. Switching Mode to Whole image hides the brush slider and reveals a single button that applies the current effect to the entire picture in one stroke, which is the fast option when you want an unreadable thumbnail or a placeholder.

Undo stores a snapshot of the canvas taken at the moment each stroke begins, and it keeps the twenty most recent snapshots. Because the snapshot is captured on pointer down, one press of Undo removes a whole drag, not a single dab. Move the strength slider after painting and only future strokes change, since what is already painted has been flattened into the canvas.

A worked example

Take a 3000 x 2000 pixel photo of a parked car. Leave the effect on Pixelate and the strength on 12. The pixelated copy is built at 250 x 167 and stretched back to 3000 x 2000, so each visible block covers a 12 pixel square of the original. Set the brush to 90, drag twice across the plate, and the registration becomes unreadable at any zoom. Press Download PNG and the file is saved as censored.png at the full 3000 x 2000 size, with the untouched parts of the photo still at their original quality.

Limits worth knowing before you start

Only PNG, JPEG and WebP files are accepted, and anything else is rejected with a message. The export is always PNG, which is lossless and therefore often larger than the JPEG you started with, especially for photographs. Very large images, above roughly 6000 pixels on the long edge, can make the canvas and the twenty undo snapshots use a lot of memory on a phone, and the tab may reload if it runs out. Blur relies on canvas filter support, which older browsers, including Safari versions before 16.4, do not implement, so if the blur option appears to do nothing on an old device use pixelate instead. There is no face detection here: you decide what gets covered, and anything you miss stays visible. There is also no crop, no rotate, no text and no shape tool, and the brush is always a circle. Because the image is redrawn on a canvas, camera metadata such as GPS coordinates is dropped from the exported PNG, though that is a side effect rather than the point of the tool.

Other tools that might fit better

To cut the sensitive area out of the frame entirely rather than blurring it, use Crop Image. If your goal is stripping location data from a photo, EXIF Viewer & Remover is the direct route. When the exported PNG is too heavy to email, shrink the dimensions with Resize Image or hit a target file size with Compress Image to KB, and the article on compressing photos for online forms sets out the upload limits people trip over. To place a solid label or a redaction note over the area instead, use Add Text to Image, and to drop a subject out of its surroundings altogether try Background Remover.

FAQ

Can anyone reverse the pixelation and see what was underneath?

No. The stamped pixels overwrite the originals on the canvas, and the downloaded PNG only contains the flattened result. There is no hidden layer holding the original detail.

Does the picture get sent anywhere to be processed?

Everything happens in your browser and nothing is uploaded to a server. The file is read from disk, drawn onto a canvas, and saved back out again.

How strong should the effect be to make a face unrecognisable?

Aim for a block size large enough that the face spans only a handful of blocks. On a face that is about 200 pixels wide, a strength of 25 to 40 leaves roughly five to eight blocks across it, which removes the features rather than just softening them.

Why is the blur doing nothing on my device?

The blur uses the canvas filter property, which some older browsers do not support. Safari added it in version 16.4. On an older device, choose Pixelate, which uses only basic drawing operations.

Can I undo more than one stroke?

Yes, up to twenty. Each press of Undo steps back to the state before one drag, and the tool keeps the twenty most recent snapshots before the oldest is discarded.