Mosaic Pixelizer
Automatically calculate mosaic size from one-hundredth of the long edge. Apply mosaic, blur, or fill effects with rectangle, ellipse, or lasso selections, entirely locally.
Upload an image. A mosaic size of longest side / 100 is auto-calculated.
Choose a selection tool (rectangle, ellipse, or lasso) and an effect, then drag on the image to define the area.
Adjust parameters and click "Export Image" to download.
Upload Image
Click or drag & drop
MOSAIC SIZE
* Recommended value is auto-calculated as longest side / 100 (rounded up)
Mosaic Pixelizer auto-calculates a mosaic size based on the longest side of your image divided by 100. Ideal for streaming, privacy protection, and more. All processing is done entirely in your browser — images are never sent to a server.
Recommended Mosaic Size by Image Resolution (Auto-calculated)
- 1280×720px (HD): Recommended 13px (1280÷100=12.8→13px)
- 1920×1080px (Full HD): Recommended 20px (1920÷100=19.2→20px)
- 2560×1440px (WQHD): Recommended 26px (2560÷100=25.6→26px)
- 3840×2160px (4K): Recommended 39px (3840÷100=38.4→39px)
- 1080×1920px (Smartphone portrait): Recommended 20px (1920÷100=19.2→20px)
- 2048×1536px (iPad): Recommended 21px (2048÷100=20.48→21px)
* Recommended value is auto-calculated as longest side ÷ 100 (rounded up)
Key Features
- 3 Selection Tools: Freely define areas with rectangle, ellipse, and lasso tools.
- 3 Effects: Choose from mosaic, blur, and fill.
- Smart Presets: An optimal mosaic size is auto-set based on the longest side of your image (longest side ÷ 100).
- Multiple Areas: Create multiple selection areas on a single image and apply effects to each.
- Movable Areas: Click and drag existing selection areas to reposition them.
Privacy & Security
- All image processing is done entirely in your browser. Images are never uploaded to a server.
Mosaic Processing in 3 Easy Steps
Import Image
Drag & drop an image into the preview area. The optimal mosaic size is auto-set based on the longest side ÷ 100.
Select Area & Apply
Choose a selection method (rectangle / ellipse / lasso) from the toolbar, then pick an effect (mosaic / blur / fill) in the right panel and define the area.
Export
Click the "Export Image" button to download the processed image as PNG. All processing is done entirely in your browser.
v1.2.0(2025/12/04)
- Unify theme colors for site-wide consistency
- Redesign settings panel (rounded corners, borders, independent style)
- Significantly improve import area visibility (always-visible dashed border, hover effects)
- Add 3-step how-to cards
v1.1.0(2025/11/07)
- Add tutorial modal shown on first visit
- Add descriptions for fully local processing and 1/100 auto-calculation to upload area
v1.0.0(2025/10/07)
- Select areas with rectangle, circle, or lasso tools and apply mosaic, blur, or fill with one click
- Smart preset auto-calculates mosaic pixel size based on 1/100 of the image's longest edge. Pixel size is freely adjustable.
- Add export feature to save processed images as PNG