Sharpen image
Sharpen a soft photo with an unsharp mask, free and in your browser with no upload. Set the amount, radius and threshold while a full-size preview shows halos before they happen; a soften mode blurs instead.
An unsharp mask: it raises the contrast at edges. Too much gives you halos, so the preview shows them at full size.
In detail
Sharpen runs an unsharp mask: it blurs a copy of the image, takes the difference, which is every edge, every eyelash and every speck of grain, and adds a multiple of that difference back so edges gain contrast. Amount, radius and threshold are all exposed.
The preview runs at one image pixel per screen pixel, because sharpening judged on a shrunken preview hides the halos and the detail alike. A threshold of 3 or 4 keeps flat areas such as sky and skin from having their own noise sharpened. A soften mode runs the same blur on its own. Sharpening makes existing edges crisper; it cannot recover detail a blurry photo never recorded.
Sharpen image at a glance
- Input
- JPG, PNG, WebP, AVIF, HEIC, GIF (first frame), BMP, TIFF, SVG and other image formats
- Output
- The original format, PNG, WebP or JPEG
- What it does
- Unsharp mask with amount, radius and threshold
- A soften mode
- A 1:1 preview you can pan
- Full-resolution export
- Batch processing
- Who it is for
- Photographers, and anyone whose photo or scan came out slightly soft.
- Limits
- Cannot restore detail that was never captured.
- Past about 150% amount, halos appear along edges.
- Privacy
- Runs entirely in your browser: no file is uploaded, and nothing is kept after you close the tab.
How to sharpen an image
- Drop your images Drag one or more images in. Each is decoded and the first readable one fills the preview.
- Choose sharpen or soften Sharpen amplifies the edge difference, up to 300%. Soften runs the same gaussian and stops there, capped at 100%, where none of the original detail is left.
- Set radius and threshold Radius, 0.3 to 8 px, is the width of the blur and so the width of the edge being worked on. Threshold, 0 to 64, leaves pixels closer to the blur than that alone — raise it to keep flat sky, water and skin from having their own noise sharpened.
- Pan around the 1:1 preview Drag the preview, or use the arrow keys, to move over the image at full size. What is on screen is what gets written.
- Apply and download Pick a format, apply, and take one file or a ZIP of the batch. The export runs at full resolution however small the preview window is.
Sharpen image: common questions
Does sharpening bring back detail in a blurry photo?
No. An unsharp mask redistributes contrast around edges that are already recorded in the file; nothing here adds detail the camera did not capture. Past roughly 150% amount the bright and dark fringes along an edge read as halos, and once written those do not come out again.
Why is the preview shown at full size instead of fitted to the window?
A downscaled preview hides fine detail and halos equally, so any judgment made on it is meaningless. The preview therefore shows one image pixel per screen pixel and you drag or arrow-key around the image. The exported file is processed at full resolution regardless of the preview size.
Why does sharpening a JPEG look grainy or blocky?
With the threshold at zero the mask amplifies JPEG compression blocks along with the real detail, because to the filter both are just differences from the blur. A threshold of 3 or 4 leaves them alone; the default is 3.