About Blur Image
Blur Image softens a picture by the radius you specify, averaging each pixel with its neighbours so that fine detail dissolves into smooth transitions. Low radii soften texture and skin; higher radii dissolve the whole structure of the image into blocks of colour.
The radius is measured in pixels, and the field accepts anything from one to fifty. It scales with the image rather than with the screen, so the same radius on a large photograph produces a much subtler effect than it would on a small thumbnail — worth remembering when you are trying to match a look across images of different sizes.
Blur is often chosen for a functional reason rather than an aesthetic one: it is the standard way to obscure a face, a licence plate or an address before an image is published. That use comes with a caveat, because the obscured detail is still present in the pixels even when it is no longer legible. A blur is a redaction only up to a point, and irreversible pixelation or cropping is the safer choice when the content is genuinely sensitive.
How to use Blur Image
- 1 Choose the image to blur.
- 2 Set the blur radius in pixels — small for a soft focus, larger for stronger obscuring.
- 3 Download the result and check the level at full size rather than in a thumbnail.
Frequently asked questions
What radius should I use to hide a face?
Enough that no features can be made out at full resolution — in practice a radius well into the tens of pixels for a face-sized region, and check the result at full size rather than in a preview. If the content is genuinely sensitive, blurring is weaker protection than cropping or pixelating.
Why does the effect look weaker than the number suggests?
Because the radius is in pixels of the original image, so it is relative to the file rather than to how it is displayed. The same setting that heavily blurs a small image will barely affect a large one.
Does blurring reduce the file size?
It can, since blur removes the high-frequency detail that compression spends the most bytes on — but the output here is written as a lossless PNG, so the saving is often smaller than expected. Compress afterwards if size matters.
Free, online, and private
Free to use
Blur Image is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Blur Image behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Method | a canvas 2D filter — ctx.filter is set to blur(Npx) and the image is drawn through it, rather than a convolution kernel written in this file |
| Radius | accepted from 1 to 50 px, default 5; anything outside that span is clamped in code rather than refused |
| Fractional radii | allowed — unlike the crop and pixelate tools, nothing rounds the radius to a whole pixel before use |
| Output format | always PNG, at the source image's own width and height |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Blur Image does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- The blur is the browser's own filter, so the radius is the only dial: there is no sigma, no kernel width, no iteration count and no quality setting, and the same number can render slightly differently in different engines.
- Nothing is downscaled before the filter runs and the result is written back as PNG whatever you supplied, so a blurred JPEG comes out as a lossless file in a very different size class from the one that went in.
- It is a whole-frame effect. There is no way to blur one region, no directional or motion blur, and no option to keep a subject sharp while the background alone is softened.
Tested and documented by itoolnet, the team that builds and maintains this site.