separable kernel · radius · png · local

Apply a Gaussian blur in your browser

Smooth an image with a true separable Gaussian kernel. Dial radius from 1 to 20 px. Output keeps full alpha and downloads as PNG.

Gaussian Blur
Source
—
no file
Output
—
PNG
Radius
4px
kernel
Sigma
2.00
gaussian
Radius 4px
input · image

image/* · runs locally · nothing uploaded

output · preview
Preview appears here
Quick Start

How it works

Pick an image, tune the options, then download the result. Everything runs in your browser.

  1. 01

    Pick an image

    Any format the browser can decode works.

    Files stay in memory as an HTMLImageElement — the original bytes are never uploaded, and EXIF metadata is preserved until you explicitly transform it.

    uploadcanvaslocaldecode
    input · bytesimage · loaded
    photo.png
    loaded · decodedcanvas · ready
  2. 02

    Set the radius

    Larger radius = softer blur but slower compute.

    Encoder quality is exposed where the format supports it — JPEG and WebP get a 0–1 quality slider; PNG is lossless. Options re-render the canvas immediately.

    radiusoptionslive previewencoderquality
    r · tunable4px · live
    sigma = max(0.5, r / 2)
    options applied · liveencoder · live
  3. 03

    Separable convolution

    Horizontal pass then vertical pass — O(N·r) instead of O(N·r²).

    Pixel work runs on the Canvas 2D context — drawImage resamples with the browser’s bilinear filter and getImageData/putImageData back per-pixel passes.

    mathrenderCanvas 2Dpreviewpx-perfect
    passes · resampled2 · px-perfect
    H · V kernel
    preview · livepx-perfect
  4. 04

    Download

    PNG with full alpha — alpha is blurred too.

    Downloads ship via a hidden anchor with an object URL — no server round-trip, and the file on disk is untouched. The output filename inherits a sensible suffix.

    exportdownloadblobclient-sideobject URL
    ok · blobready · saved
    photo-blur.png
    shipped · ready to shipsuccess
Pro tips

Browser-only image work that scales

Convert with quality control

JPEG/WebP let you pick a 0–1 quality. Default 0.92 is a good compromise of size and visible quality.

PNG isn’t free

Use PNG only for transparency or sharp edges. For photos, WebP is smaller at the same perceived quality.

Strip EXIF for privacy

Photo EXIF often contains GPS, camera model, and timestamps. Strip before sharing public uploads.

Watch the colour profile

Convert to sRGB before web export. Wide-gamut images render oversaturated in non-managed browsers.

AVIF when it’s available

AVIF beats WebP on size at the same quality. Detect support via <picture> with fallbacks.

Lazy-load below the fold

Add loading="lazy" on <img>. The browser handles scheduling — no IntersectionObserver needed.

Use Cases

When to use this tool

Common workflows it speeds up.

Background blur

Soften a photo to use behind text. Decoded into a Canvas 2D context — original bytes never leave the tab, so you can process customer-uploaded photos, internal screenshots, or sensitive diagrams without privacy concerns.

px-perfect

Privacy

Blur faces and licence plates before sharing. Encoders expose quality 0–1 where the format supports it (JPEG, WebP); PNG and AVIF stay perceptually lossless. Pick 0.85 for web, 0.95 for archival, 0.7 for thumbnails.

quality-tunable

Placeholder skeletons

Generate low-quality image placeholders. Pair with the EXIF Stripper before sharing user-uploaded photos publicly. Camera serial numbers, GPS coordinates, and timestamps often hide in image metadata and leak more than the picture itself.

format-aware

Stylised art

Soft-focus effect for portrait shots. Output preserves colour profile (sRGB) so it renders consistently across browsers, monitors, and print pipelines. Wide-gamut workflows can opt into Display P3 for modern Apple devices.

EXIF-safe

Image kernels demo

Visualise what convolution actually does. Re-runs only on option changes, never on window resize, so the canvas stays responsive on large images. drawImage uses the browser's bilinear filter for fast resampling.

client-side

Glassmorphism

Blur a screenshot for frosted-glass UI mocks. Downloads as .png, .jpg, .webp, or .avif with the correct MIME so editors apply native handling on save. The filename inherits a sensible suffix derived from the input.

compression-ready
FAQ

Frequently asked questions

A 2-D Gaussian can be decomposed into two 1-D convolutions. This drops complexity from O(N·r²) to O(N·r) with bit-identical output.
Yes — alpha is convolved alongside RGB so edges of transparent regions feather correctly.
Beyond 20 px the cost gets meaningful without a visible quality jump. Resize the source down for huge blurs.
Output is capped at 1600 px on the long edge for snappy preview. Use a desktop tool for full-res blurs.
No. The blur runs locally in your browser — nothing leaves the device.
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