Pixelate Image

Pixelation is a reliable way to hide details because each block becomes a single flat colour; the original pixels inside the block are gone from the saved file. Use blocks that are at least as large as a letter or a facial feature, which means a higher strength for small details in large photos.

It works well for screenshots of chats, emails and bank statements: select the name, account number or address and pixelate it before posting.

Pixelate the whole image with a large block size for a retro video game style, then use it as an avatar or a background. Smaller blocks give a subtle mosaic. PNG images keep their transparency, so pixelated logos and stickers still have see-through backgrounds.

The strength slider sets the size of each square as a share of the picture, up to 6% of its longest side, so the same setting looks the same on a phone screenshot and a large photo. Low values give a fine mosaic in which shapes are still clear; high values give big blocks that hide everything inside them.

As a rule of thumb, a block should be bigger than the detail you want to hide: larger than a letter for text, larger than an eye for a face. Squares start at the corner of the selected area, so the mosaic lines up neatly with the box you drew. The saved image keeps its full resolution and format, and nothing is sent to a server, which is important when the picture contains private information you are trying to protect.