Image Pixelator & Mosaic Effect
Blocks, dots or diamonds — a deliberate mosaic effect rather than a censorship tool.
What the image Pixelator & Mosaic Effect does
Pixelation reduces an image to a grid of solid blocks, each one the average colour of the area it covers. This tool does that by an elegant shortcut: it draws the image into a tiny canvas, one pixel per tile, letting the browser's high-quality downscaler compute the averages, then paints each of those pixels back as a large shape. The result is smoother than naively sampling one pixel per block, because every pixel in the original contributes.
Four tile shapes are available. Squares give the classic blocky look. Circles produce a dot mosaic that reads as halftone or pointillism, especially with a gap between tiles. Diamonds rotate the grid 45 degrees. Offset rows shift alternate lines by half a tile, which breaks up the rigid grid and looks more like real mosaic tiling.
Two extras change the character considerably. Adding a gap and setting its colour turns the effect from a filter into something that reads as constructed — tiles on a wall, pixels on a screen, beads on a board. Posterising snaps each channel to four levels, cutting the palette to 64 colours and giving a deliberately synthetic, retro-computer look.
One thing this tool is not: a redaction method. It applies to the entire image, and even when applied selectively, pixelation of text or faces has been shown to be reversible in many cases. The Privacy Blur Tool covers that job properly and explains the limits honestly.
How to use it
- Load your image and set the block size — larger blocks mean a more abstract result.
- Pick a tile shape. Circles with a small gap read as a halftone dot pattern.
- Set a gap colour that suits the image; a dark gap makes tiles look lit from behind.
- Turn on posterising for a deliberately retro, limited-palette look, then download.
A worked example
The same photograph at four settings:
| Settings | Effect |
|---|---|
| 6px squares, no gap | Subtle — looks like a low-resolution image |
| 20px squares, no gap | Clearly blocky; the subject is still recognisable |
| 20px circles, 4px gap, dark background | Reads as a dot mosaic or LED panel |
| 28px squares, posterised | Eight-bit game aesthetic, 64 colours |
A useful rule for the block size: a face stays recognisable until the blocks are roughly a tenth of the face's width, and becomes an abstract pattern at around a third. That is a statement about aesthetics rather than privacy — recognisability by a human is not the same as irrecoverability by software.
Frequently asked questions
Can pixelation be reversed?
Often, yes — which is why this is presented as an art effect rather than a privacy tool. Pixelation is a known, deterministic transformation, and researchers have repeatedly recovered pixelated text by testing candidate strings through the same process until the output matches. Use the Privacy Blur Tool for anything sensitive.
Why does my mosaic look blurry rather than blocky?
The block size is probably too small relative to the image. At 4 pixels on a 3000-pixel-wide photo, the tiles are invisible at normal viewing size. Increase the block size, or reduce the image first with the Resizer.
What does posterising do?
It snaps each colour channel to four levels, cutting the palette from 16 million colours to 64. Combined with large blocks it produces the limited-palette look of early computer graphics. It also makes the resulting PNG considerably smaller.
Can I pixelate just part of an image?
Not with this tool — it applies to the whole image by design. The Privacy Blur Tool lets you select regions and covers exactly that case.