Blur Image
Blur Image
Apply Gaussian blur to your images for privacy or artistic effects
- Runs in your browser
- Nothing uploaded
- No sign-up
- Free, no daily limits
- 1Add your file
- 2Choose settings
- 3Download
Drop an image here
Choose a fileSelect an image to blur · up to 20 MB · nothing is uploaded
100% Private: All processing happens in your browser. Your files never leave your device.
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Blur Image applies uniform Gaussian defocusing across any picture using client-side canvas filters. With a slider ranging from 1px to 50px in single-pixel increments, you can calibrate the exact level of softening needed for your graphic. Dragging the control updates an on-screen preview in real time. Clicking Apply Blur & Download renders the final output at the original source resolution, ensuring full pixel dimensions without downsampling.
Gaussian blur operates globally across the entire canvas frame rather than targeting isolated facial regions or license plates. If you need to obscure a specific area while keeping the surrounding scene sharp, crop around the target region using Crop Image before applying the blur filter. For hard-edged mosaic tiles instead of smooth optical defocusing, use Pixelate Image. Output files export as PNG for PNG inputs, or as high-quality JPEG at 0.95 quality for other formats.
How it works
1. Upload an image
Select or drop a single image file into the tool. The processor supports formats like JPEG, PNG, and WebP up to 20 MB.
2. Set the blur radius
Move the slider between 1px and 50px. The live preview updates instantly to show the degree of optical smoothing.
3. Apply blur filter
Click Apply Blur & Download. The canvas renders the effect at original image resolution using hardware-accelerated filters.
4. Save the blurred image
Click Download Blurred Image to save your finished file directly to your device storage.
When you'd use it
Softening photographic backgrounds for text readability
Apply a 10px to 15px blur to hero banners or presentation slides so overlaid typography, icons, and callouts stand out clearly.
Redacting sensitive personal details in cropped documents
Crop tightly around account numbers, physical addresses, or signatures, then apply a heavy 25px blur to eliminate readable glyphs.
Simulating shallow depth of field in portraiture
Use a gentle 2px to 4px radius across portrait shots to soften harsh digital sensor noise and replicate wide-aperture lens characteristics.
Generating abstract color backdrops and UI wallpapers
Push the slider to 45px or 50px on vibrant outdoor scenery photos to convert complex compositions into smooth, modern gradient backdrops.
How does Gaussian blur soften pixels and reduce file size?
The blurring pipeline assigns `ctx.filter = blur(${blurRadius[0]}px)` to an HTML5 canvas before drawing the source bitmap. A Gaussian blur functions mathematically as a spatial low-pass filter, averaging adjacent pixel values using a bell-shaped normal distribution curve. This process eliminates high-frequency spatial transitions such as sharp edges, skin textures, and typography boundaries.
During testing on our standard benchmark photo (2048 x 1536 px, 2,678,144 bytes, or 2,615.4 KB), applying a 15px blur radius produced a finished file of 269,032 bytes (262.7 KB). Because JPEG compression relies on the Discrete Cosine Transform (DCT) to quantize high-frequency coefficients, removing sharp contrast variations allows the compression algorithm to store smooth gradients in a fraction of the original byte footprint, cutting file size by nearly 90%.
Blur radius recommendations for redaction and privacy
Selecting the correct radius depends on your privacy goals and viewing scales. A subtle 3px blur softens minor noise without hiding characters, making it unsuitable for confidentiality. For document redaction, 10px obscures small print but leaves major headings legible. Achieving complete anonymity for faces, vehicle registration plates, and credit card numbers requires a radius of 20px or higher at full resolution.
The following table details redaction efficacy across common slider settings, verified on our 2048 x 1536 px sample image.
| Blur Radius | Defocus Strength | Text Legibility | Identity Protection at 100% Zoom |
|---|---|---|---|
| 3px | Subtle softening | Body text easily readable | Identities fully recognizable |
| 10px | Moderate defocus | Fine print obscured, headlines legible | Features partially recognizable |
| 20px | Heavy redaction | Completely unreadable | Faces and number plates unidentifiable |
| 40px to 50px | Extreme abstraction | Zero character recognition | Total loss of subject geometry |
Source: TryDocsy canvas benchmark on sample-phone-photo.jpg (2048 x 1536 px), tested on Chrome 156, checked October 29, 2026
Why does the blur effect cover the entire image canvas?
This utility applies a uniform filter pass across the entire image raster. It does not include automated computer vision models to detect faces or bounding boxes, nor does it provide an interactive localized brush. Applying full-frame blur ensures rapid client-side performance without loading heavy multi-megabyte machine learning weights into your browser.
If your goal is to obscure only one person in a crowd or a single license plate on a car, the recommended privacy workflow is simple: crop around the sensitive region first with Crop Image, blur that cropped snippet, or overlay a protective stamp with Add Watermark. You can also remove tracking tags with EXIF Remover.
What format caveats and transparency behaviors should you expect?
The export format depends on your input file type. Files uploaded as PNG export as PNG images at 100% original dimensions. All other inputs, including JPEG, WebP, and GIF, export as JPEG files compressed at 0.95 quality. Note that unlike some specialized masking tools, this component does not fill a white background matte before exporting non-PNG files. If you upload a transparent WebP or GIF, areas of transparency will render as black pixels in the JPEG output.
Re-encoding the canvas into a new blob strips all embedded EXIF metadata, removing GPS coordinates and camera serial numbers automatically. For fine-art photo retouching that requires selective gradient masking or automated subject detection, dedicated desktop editors such as GIMP or Photoshop are better choices.
Frequently asked questions
Can I blur only a face or license plate while keeping the rest sharp?
The tool applies blur across the entire frame. To obscure a specific area, crop tightly around that section first using our crop tool, then apply the blur filter.
Why did my file size decrease so dramatically after applying blur?
Gaussian blur removes high-frequency edge details. JPEG compression compresses smooth, low-frequency color gradients far more efficiently, reducing file size significantly.
Will blurring a transparent WebP image keep its transparent background?
Only PNG files retain transparency on export. Other formats export as JPEG, which does not support alpha channels, causing transparent areas to appear black.
Does the blur filter reduce the pixel resolution of my photo?
No. The final download retains the exact original pixel width and height of your uploaded photo; only the pixel color values are defocused.
What is the recommended radius to make text completely unreadable?
A radius of 20px or higher renders document text and identification numbers completely illegible at 100% zoom on high-resolution images.
What is the upload size limit for image blurring?
The tool accepts individual image files up to 20 MB, checked during the upload step before canvas processing begins.