Image Pixelator — Mosaic & Block Effect

Drop any photo into the Image Pixelator and it replaces every tile of pixels with that tile's average colour, producing the blocky mosaic effect seen in redacted images, retro game art, and privacy-protecting face blurs. Three styles are available: square blocks for the classic 8-bit look, horizontal bars for a CRT-scanline aesthetic, and circular dots for a halftone-style result. All processing runs in your browser via the Canvas API. Nothing is uploaded.

The block-size slider runs from 2 px to 64 px. At 2 px the effect is subtle, barely distinguishable from light blur. At 64 px each tile covers a large region of the image and faces or text in that region become unreadable. Five quick-preset buttons (Fine 4 px, Medium 12 px, Coarse 24 px, Large 40 px and Mega 64 px) let you jump to common sizes without touching the slider.

Getting Your First Pixelated Image

1. Drop a JPEG, PNG or WebP file onto the upload zone, or click to open the file picker. Files up to 10 MB are accepted.
2. Choose a Mosaic style: Square for the default block effect, H-Bars for horizontal scanlines, or Dots for circular tiles.
3. Drag the Block size slider or press a preset. The preview updates on every change — no Apply button required.
4. Press Download to save the result. The exported file is rendered at the image's full native resolution, not the capped preview size, so a 4000 × 3000 photo exports at 4000 × 3000.

How the Block-Averaging Algorithm Works

The image is divided into a grid of tiles of the chosen pixel size. For each tile the tool reads every pixel in that region and computes separate arithmetic means for the R, G and B channels. The tile is then filled with that averaged colour. In Square and H-Bars modes this is a plain filled rectangle; in Dots mode a circle inscribed at 90% of the tile radius is drawn instead, leaving the background colour of the canvas (the page's background) visible in the gaps between circles. The same algorithm drives the export, with the block size scaled proportionally to the native resolution so the visual result is pixel-for-pixel identical to the preview.

Size, Performance and Export Format

• The preview canvas is capped at 900 px on the longest edge for speed. A 6000 px wide photo is decoded at 900 px for the live preview, keeping slider changes instant on mid-range hardware.
• Download re-renders from the original at full resolution. Block size scales up automatically — a 16 px block on the preview of a 6×-scaled photo exports as a 96 px block on the 6000 px image.
• PNG input exports as PNG to preserve transparency. JPEG and WebP inputs export as JPEG at 0.95 quality. Rename the file before uploading if you need a specific output format.
• The Dots mode gap colour comes from the canvas background, which matches the page's background colour. In dark mode those gaps are dark; in light mode they are near-white. This is intentional — the gaps are not part of the image data.