Free Online Mosaic Effect Tool — Pixelate Images Instantly
Easily apply mosaic (pixelation) effects to your images with our free online tool. Use the intuitive block size slider to control the pixelation intensity — from fine-grained pixelation for artistic effects to large blocks for privacy protection. The classic 'censor bar' mosaic look is achieved by dividing the image into colored blocks. All processing happens in your browser for complete privacy — your images never leave your device.
Upload the image you want to pixelate by dragging it onto the upload area or clicking to browse your files.
Drag the block size slider to control the pixelation intensity. Larger block sizes create a more pronounced mosaic effect. The preview updates instantly as you adjust.
Download your pixelated image in its original format when you're satisfied with the result.
Tips for Using Mosaic / Pixelation Effects
- Small block sizes (2-5 px) create a subtle pixel art effect that can add an interesting retro game aesthetic to your images.
- Medium block sizes (6-12 px) are ideal for obscuring sensitive information like faces, license plates, or personal details in photos before sharing online.
- Large block sizes (20-100 px) produce a dramatic mosaic effect that completely obscures details while preserving the overall color composition of the original image.
Frequently Asked Questions — Mosaic / Pixelation Effect
Is the mosaic effect tool really free?
Yes, completely free. No registration, no hidden charges, no watermarks, and no file size limits. All processing happens locally in your browser — your images never leave your device.
How does the pixelation effect work?
The pixelation effect works by first downscaling your image to a much smaller size based on the block size setting, then scaling it back up to the original dimensions using nearest-neighbor interpolation. This creates the characteristic blocky 'mosaic' look where groups of pixels are merged into larger colored squares. The process is incredibly fast because it leverages the browser's native canvas scaling.
What does the block size slider do?
The block size slider controls how large each pixel block appears in the final image. A block size of 1 means no pixelation (original image). A block size of 10 means every 10×10 pixel area becomes a single colored block. Higher values create a more aggressive mosaic effect. The slider ranges from 1 to 100.
What image formats are supported?
JPG, PNG, WebP, BMP, AVIF, GIF, TIFF, SVG, HEIC and more. The pixelated result is saved in your original upload format, preserving compatibility.
Is mosaic effect good for privacy protection?
Yes! Mosaic/pixelation is widely used for privacy protection in news media and online content. By obscuring specific areas with large pixel blocks, it prevents recognition of faces, license plates, and other sensitive information. For maximum privacy protection, we recommend using block sizes of 10 or higher.
What is the difference between mosaic and blur for privacy?
Both mosaic (pixelation) and Gaussian blur can be used for privacy protection, but they produce different visual results. Mosaic creates blocky, clearly artificial pixel squares that make it obvious an area has been intentionally obscured. Blur creates a smooth, soft transition that can sometimes be reverse-engineered on low-blur settings. For privacy, either works well — mosaic is generally considered stronger for prevention of recognition at moderate settings.
How large of an image can I process?
Our tool handles images up to 50 megapixels (50,000,000 pixels total). If your image exceeds this limit, you'll see a warning and can try a smaller version or reduce the resolution before applying the mosaic effect.