Sharpen Image
Sharpen a soft or slightly out-of-focus photo using an unsharp mask: the image is compared against a blurred copy of itself and the difference is added back, which strengthens edges without touching flat areas. Amount controls how strong the effect is, radius controls how wide an edge has to be to count, and the threshold leaves small differences alone so film grain and JPEG noise are not sharpened along with real detail. Nothing is uploaded.
How strongly edges are boosted. Past about 150% most photos start to show halos along high-contrast edges.
How wide an edge has to be before it counts. Small values sharpen fine detail; larger values add local contrast.
Differences smaller than this are left alone, which stops film grain and JPEG noise from being sharpened along with real detail.
Frequently asked questions
How does sharpening actually work?
An unsharp mask blurs a copy of the image, subtracts it from the original to isolate the edges, then adds that difference back at the strength you choose — which is why it strengthens edges and leaves flat areas untouched.
Can sharpening fix a badly blurred photo?
Sharpening increases the contrast at edges that are already present; it cannot recreate detail the camera never captured, so a genuinely out-of-focus shot will look crisper at the edges but no more detailed.
What does the threshold setting do?
The threshold sets how big a difference has to be before it is sharpened, so raising it leaves small variations — grain, sensor noise, JPEG artefacts — alone while still sharpening real edges.
Why does my sharpened photo have light and dark outlines?
Those halos are the unsharp mask overshooting: the amount is too high or the radius too wide for the picture, so pulling either back until the outlines disappear gives a cleaner result.
What settings should I start with?
An amount of around 80–120%, a radius of 1–2 pixels and a small threshold suits most photographs, with larger radii reserved for adding broad local contrast rather than fine detail.
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