The tool reduces the image to a coarse working grid and scales it back without smoothing. A larger pixel-size setting produces fewer, larger blocks; the exported image keeps the source canvas dimensions.

Choose the block size by purpose

Small blocks soften fine detail while keeping the subject recognizable. Large blocks create a deliberate retro or abstract look. Check the result at its intended display size—a mosaic that looks strong in a thumbnail may reveal more detail when enlarged.

Not a secure redaction method

Pixelation changes the visible pixels, but it is not a guarantee that a person, number plate or sensitive detail is impossible to infer. Crop confidential content out or replace it with an opaque covering in a workflow designed for disclosure control. Do not treat this visual effect as document redaction.

Formats and failed uploads

Processing happens in the browser and recognized JPG, PNG and WebP files keep their output format. Very large images can exceed mobile memory. If a file cannot be decoded, convert it first with Image Converter; use Image Blur when a smooth effect is preferred.

Why pixelation looks the way it does

For the reasoning behind block size, when a mosaic reads as stylistic rather than censoring, and why the effect is not a disclosure control, read The Humble Pixelate Effect. Use Redact PDF when content must actually be removed rather than obscured.