Free browser tool

Image mosaic / blur

Apply a mosaic effect to a selected rectangular area of an image.

Input and settings

How to use it

Apply a mosaic effect to one rectangular part of an image and save the result as PNG. Position and size are entered as percentages of the full image, so the same controls work across different source resolutions.

Choose an image and set X/Y for the top-left of the area.
Adjust width, height and mosaic block strength.
Check that the intended content is fully obscured, then download the PNG.

Position: X / Y: 0–100%
Area: width / height: 1–100%
Block strength: 2–100
Output: PNG

Start with a broad center area when hiding a face

If the face is near the center, begin around X 25, Y 25, width 50 and height 50, then narrow the rectangle after confirming the preview.

Mosaic is a visual obfuscation effect, not a guarantee that sensitive information is permanently unrecoverable. For serious privacy needs, also consider removing/cropping the source region and handling the original file carefully.

X and Y are percentages, not source pixels

X 25 means one quarter of the image width from the left, and Y 25 means one quarter down from the top. This makes the controls resolution-independent.

Higher block strength creates larger visible squares

When hiding small text, increase the effect until the character shapes are no longer legible rather than judging only by whether the area looks blurred.

Leave a margin around the sensitive subject

A rectangle that ends exactly on a face or license-plate edge can leave identifying detail visible. A slightly wider area is safer for public output.

Screenshots often need careful previewing

For email addresses or IDs, begin with a larger rectangle and stronger block effect, then reduce the area only after confirming the text cannot be read.

The saved file is PNG

If the final workflow needs JPEG or another format, apply mosaic first, verify the result, and convert the accepted output afterward.