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Sharpen an image

Crisper edges for a slightly soft photo, previewed live and made on your device.

Make a soft photo crisper with an adjustable unsharp mask and a live preview. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The size limit is your device’s memory, and phones hold less; give the page a short while after one visit to save itself for offline use, and then it works offline.

Drop photos to sharpenor click to choose files. Batches welcome.
    Working…

    Done

    Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.

    Phone shots taken in low light, photos that were resized a few times, and pictures scanned from prints often look slightly soft: nothing is badly out of focus, but edges lack bite. Sharpening brings that bite back by increasing the contrast right at the edges, the same unsharp mask photographers have used since darkroom days.

    The page opens with Sharpen at 40. Watch fine detail in the preview, such as eyelashes, fabric or lettering, and raise it until those look crisp; stop as soon as a thin light outline appears along dark edges, which is the sign of over-sharpening. The strength scales with the photo’s size, so what you see in the preview is what the full-size file gets.

    Sharpening works on what the camera captured. A photo that is really blurred, from motion or a missed focus, will gain edges but not detail; for small or pixelated pictures, the AI upscaler is the better tool, since it redraws detail rather than only boosting contrast.

    How it works

    1. Drop the photos.
    2. Set Sharpen until edges look crisp but not outlined.
    3. Press Apply and save them.

    In your browser, not on a server

    Your browser decodes each photo (libheif or the Squoosh decoders step in for HEIC, AVIF and JPEG XL) and draws it on a canvas in your tab. Brightness is a gamma curve and contrast an S-shaped stretch around middle grey, both applied through a 256-entry lookup table per channel; warmth shifts red against blue, saturation mixes each pixel with its own Rec. 709 brightness, and sharpening is an unsharp mask: the picture plus a share of its difference from a blurred copy. The browser then saves the canvas as JPG, PNG or WebP.

    Compared with upload-based tools: Online photo editors upload the picture for a slider move a phone could do offline, and many add a watermark or keep the upload. Here the photos stay on your device, a whole batch gets the same settings in one go, and the result is compressed only once.

    Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.

    Questions

    Should I sharpen before or after resizing?

    After. Shrinking a picture softens it slightly, and enlarging even more, so sharpen as the last step, at the size the photo will be seen. If you are making it smaller with the compress tool, run that first and sharpen the result here.

    Why does my photo look grainy after sharpening?

    Sharpening also boosts noise, the fine speckle in dark or low-light areas. Use a lower setting for night shots, or lower Contrast a little at the same time, which calms the grain.

    Can it fix a blurry face or unreadable text?

    Only if it is slightly soft. It cannot reconstruct features or letters that were never recorded clearly. For text you need to read, try Image to text, which is often better at reading soft text than eyes are.

    Is the file uploaded anywhere?

    No. There is no server in this process. The page is a static file and the work is done by code running inside your browser tab. Give the page a short while after one visit to save itself for offline use; then you can turn off Wi-Fi and it still works.

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