Real unsharp mask, not a contrast hack
The filter computes a Laplacian of the image and adds a scaled amount back to each pixel, so only edges are accentuated while flat areas stay clean and smooth.
Sharpen Image
Bring back crisp edges in soft or slightly blurry photos with an unsharp mask.
- Upload
- Single file · 25 MB max
- Privacy
- Nothing is uploaded
- Cost
- Free · no sign-up · no watermark
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Processed entirely on your device
Your file is read, transformed and re-encoded inside this browser tab using JavaScript. There is no upload endpoint — nothing leaves your machine, nothing is stored, and the result is created as a local object URL that disappears when you close the page.
Overview
About the Sharpen Image
Sharpen any photo with an adjustable unsharp mask that boosts edge contrast without adding halos. Runs on your device — nothing is uploaded.
What an unsharp mask actually does
Sharpening does not invent detail — it increases the contrast right along existing edges. The tool measures how much each pixel differs from its neighbours (its Laplacian) and adds a scaled version of that difference back, so a soft light-to-dark transition becomes a snappier one. Flat regions have almost no edge signal, so they stay smooth.
Using the amount slider well
Start near 40-60% for portraits and product shots, where over-sharpened skin looks unpleasant. Landscapes, architecture and text screenshots tolerate 80-130%. Push toward 200% only for a deliberate, crunchy graphic look, and always judge at full size rather than in the thumbnail preview.
Order of operations
Sharpen after cropping and resizing, because those steps soften edges and would undo the effect. If an image is noisy, denoise first and sharpen afterwards; sharpening noise makes it far more visible.
Local and lossless
The convolution runs on an in-browser canvas at native resolution and is exported as PNG, so your source file is never uploaded and the sharpened result keeps full fidelity.
Step by step
How to use the Sharpen Image
Drop a soft or slightly blurry image onto the upload area.
Raise the sharpen-amount slider; edges gain contrast as you drag.
Stop before halos or grit appear — usually 40-100% is plenty.
Download the sharpened PNG at full original resolution.
Why use it
Benefits and common use cases
What this tool is good for, and what it deliberately does not try to do.
Rescues slightly soft shots
Missed focus, motion softness and heavy compression all leave edges mushy; a modest sharpen restores the bite that makes a photo look crisp and finished.
Live, local and lossless
Every slider position re-renders from your untouched source on an in-browser canvas and exports PNG, so nothing is uploaded and quality never stacks.
Questions
Frequently asked questions
Short, honest answers about quality, limits and privacy.
How much sharpening is too much?
When bright edges start showing dark-light halos, or flat areas like sky turn gritty, you have gone too far. Back the slider down until the artefacts disappear.
Does sharpening fix a truly blurry photo?
It helps mildly soft images a lot, but it cannot recover detail that was never captured. For a badly out-of-focus shot, sharpening mainly amplifies blur edges and noise.
Should I sharpen before or after resizing?
Sharpen last, after any resize or crop, because scaling softens edges. Sharpening a full-size image and then downscaling throws most of the effect away.