What an unsharp mask does
Despite the name, an unsharp mask makes a photo look sharper. It compares each pixel with a blurred copy of the image. Where they differ, there is an edge, and the edge is exaggerated a little: the light side made lighter, the dark side darker. The eye reads that extra contrast at edges as sharpness.
It is a conventional edit, ordinary image arithmetic with no model. It improves photos that are slightly soft from a lens, from resizing or from mild camera shake. It cannot fix a photo that is badly out of focus, because there are no edges left to strengthen.
It also helps after shrinking a photo, which tends to soften fine edges.
Amount, Radius and Threshold
The three sliders work together, and each one solves a different problem.
- Amount, from 0 to 300 percent, sets how strongly edges are boosted. Start around 80 to 120 percent and go up only if needed.
- Radius, from 0.5 to 5 px, sets how wide the boosted band around each edge is. Small values bring out fine texture such as hair and fabric. Large values add punch to bigger shapes but cause visible halos sooner.
- Threshold, from 0 to 40 levels, skips differences smaller than its value. That protects smooth areas: at 0, every tiny variation in skin and sky is sharpened too, which looks gritty. A threshold of 4 to 10 usually keeps faces smooth while edges still sharpen.
Signs you have gone too far
Look for bright or dark outlines along strong edges, like a roofline against the sky. That halo means Radius or Amount is too high. Look at faces and plain walls: if they have turned grainy, raise Threshold. Check at 100 percent zoom, then again at the size people will see, because sharpening that looks right on a large screen can look harsh on a phone.
Hold to compare and the before and after slider are the quickest checks. Apply makes the result a new version in History, so you can try a second setting and keep whichever is better.
Where it fits in an edit
Sharpen last. Brighten, correct color and resize first, then sharpen the final version. If you are going to enlarge the photo, use Image upscaler first; sharpening before enlarging just makes bigger halos.
Sharpening suits detail-rich subjects such as architecture, landscapes and product textures. Portraits usually want a lighter touch and a higher Threshold, so eyes and hair gain definition while skin stays soft.
What it will not do
- It cannot rescue a photo that is badly out of focus or heavily blurred by motion.
- Too much Amount or Radius causes halos along strong edges.
- With a low Threshold it also sharpens noise and grain.
- Sharpening applies to the whole image, not to chosen areas.
Devices and downloads
No download — ordinary image arithmetic. No model is involved, so it does not depend on WebGPU or WebAssembly. Slider changes preview live on a screen-sized copy, and Apply sharpens the full-resolution photo in this tab.
Instant edit: Ordinary image arithmetic. No model, no download, works in any modern browser. See what is stored on this device.
Step by step
- Open the photo. Drop, paste or choose the soft image.
- Set Amount and Radius. Begin near 100 percent and a small radius, then adjust.
- Raise Threshold. Increase it until skin and sky stop looking gritty.
- Apply and check. Compare at full size and at viewing size, then export.
Questions about photo sharpener
What Threshold setting keeps skin smooth when sharpening?
Try 4 to 10. Differences below that level are left alone, so pores and gentle skin gradients are not roughened while real edges still sharpen.
Can sharpening fix a photo that is out of focus?
Only slightly soft photos. A badly out-of-focus picture has no edges left to strengthen, so sharpening mostly adds noise.
Why are there bright outlines around edges after sharpening?
Those are halos from too much Amount or too large a Radius. Lower Radius first, then Amount.
Should I sharpen before or after resizing a photo?
After. Resize or enlarge first, then sharpen the final size, so the edge boost matches the pixels people actually see.