Censor Image (Blur or Pixelate Part of a Photo)

Before you post a screenshot or a street photo, you may need to hide a face, a licence plate, a name, a phone number or an address. This tool covers the areas you choose with a mosaic, a blur or a solid bar, on one photo or a batch, and gives you a guide image with a 10% grid so you can place the boxes precisely. It runs in your browser, so the uncensored photo never leaves your device.

How to use this tool

1. Choose the photo (or several photos with the same layout, such as screenshots).
2. Run it once with the guide switched on and read the positions of what you want to hide from the 10% grid.
3. Enter one box per line as left, top, width, height in percent — or pick the whole image, top or bottom strip.
4. Choose pixelate, blur or solid bar and its strength, run again and check the result.
5. Download the censored image; your original file is not changed.

Formula

Mosaic block colour = Σ(colour × alpha) ÷ Σ alpha over the block; box pixels = percent × image size ÷ 100

Mosaic blocks start at the box’s top-left corner and are “block %” of the image width wide. Blur uses a Gaussian with σ = strength % of the width, approximated by three box blurs, and samples 3σ beyond the box so the edges blend with the surroundings; only pixels inside the box change. A solid bar replaces the pixels completely and is the only method that cannot be undone or guessed.

Example

On a 1600 × 1200 px street photo, a plate in the box 62, 70, 14, 6 covers x 992–1216 and y 840–912 px (224 × 72 px). With the default 4% mosaic, blocks are 64 px wide, so the plate becomes about 4 × 2 flat squares and the characters are gone.