How to use Sharpen image
- 1
Open the photo
Drop or paste a JPG, PNG, WebP or HEIC picture of up to 25 MB. A moderate sharpening is applied right away and the before-and-after slider opens.
- 2
Set amount and radius
Amount controls how strong the effect is; Radius decides whether fine texture (0.5–1.5 px) or larger edges (2–4 px) get the boost.
- 3
Protect smooth areas
Raise Threshold until skin, sky and walls stop looking grainy while edges stay crisp. Zoom into the comparison to judge it at 100%.
- 4
Download
Save the sharpened copy at full resolution in its original format, or pick JPG, PNG or WebP.
Limits and Pro
Up to 10 photos in the list and 25 MB per photo, each sharpened on its original pixels.
Pro processes lists of up to 500 photos of up to 4 GB each. See Pro
About Sharpen image
Sharpening makes an image look crisper by increasing contrast along edges. This page uses an unsharp mask, the method darkroom printers invented and every photo editor still relies on: it blurs a copy of the picture, measures how much each pixel differs from that blurred copy, and adds the difference back on top. Where there is an edge, the light side gets a little lighter and the dark side a little darker, so outlines, eyelashes, text on a sign or the grain of wood stand out.
The effect is calculated on brightness only, then applied equally to red, green and blue, which avoids the coloured halos that sharpening each channel separately can produce. Three controls shape it. Amount (up to 300%) is the strength. Radius, in pixels, sets the size of detail that gets emphasised. Threshold leaves pixels alone when their difference is small, keeping noise and gentle gradients smooth. The before-and-after slider supports zoom, so you can inspect the result at pixel level before saving.
Typical uses are photos that are a touch soft from a phone lens, product shots, scans of documents and pictures that were resized smaller, which always loses some crispness. What sharpening can't do is recover detail that was never recorded: a strongly out-of-focus or motion-blurred photo stays blurred, just with harder edges and more visible noise. This page doesn't use generative AI to invent missing detail. If the picture is also too small, enlarge it with the AI upscaler first and sharpen afterwards.
Privacy
The unsharp mask is computed by a Web Worker running in your browser tab, at full resolution, and the file is encoded on your device. The photo is never uploaded and nothing about it is stored.
Features
Unsharp mask
Amount, radius and threshold, like in professional editors.
Before and after
A zoomable comparison slider to judge detail at 100%.
No colour fringes
Sharpening works on brightness, so edges don't gain coloured halos.
Full resolution
The download is processed on the original pixels, not the preview.