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Image Sharpener

Bring back edge detail with unsharp masking.

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Quick Tool Overview

The Image Sharpener uses unsharp masking — the same method every serious editor uses — with amount, radius and threshold as separate controls. The threshold is what makes it usable: it stops flat areas like skies and skin having their noise amplified, which is where over-sharpening always shows first.

What it does
Increases edge contrast to restore crispness
You give it
A slightly soft photo
You get back
A sharper-looking version
Best for
Resized images and JPEG-softened photos
Image Tools Free, unlimited use No sign-up Runs in your browser

About the Image Sharpener

Sharpening cannot recover detail that was never captured — a genuinely out-of-focus photograph stays out of focus. What it does is increase local contrast at edges, which the eye reads as crispness, and that fixes the softness resizing and JPEG compression introduce.

The method is unsharp masking, the same one every serious editor uses: blur a copy, subtract it to isolate the edges, and add those edges back at a strength you choose. The threshold control is what separates this from a slider labelled "sharpen" — it stops flat areas like skies and skin from being sharpened, which is where over-sharpening becomes obvious as amplified noise.

Key features of the Image Sharpener

Proper unsharp masking

A blurred copy is subtracted to isolate edges, which are added back amplified — not a fixed convolution kernel.

Threshold control

Only differences above a set size count as edges, so skies and skin keep their smoothness instead of gaining noise.

Radius control

One pixel for fine detail, two or three for a broader lift — the difference between crisp and crunchy.

Halo warning

The page explains what over-sharpening looks like so you can spot it before you download.

Straight about limits

It says clearly that focus blur cannot be recovered, rather than implying a fix that does not exist.

How to use the Image Sharpener

  1. 1

    Load a slightly soft photo

    Resized images and JPEG-compressed ones benefit most.

  2. 2

    Raise the amount

    Start low. Halos around high-contrast edges mean you have gone too far.

  3. 3

    Set the radius

    Around 1 pixel for fine detail, 2 to 3 for a softer overall lift.

  4. 4

    Raise the threshold

    This protects skies and skin from having their noise sharpened.

Frequently asked questions

No. Focus blur destroys information that no amount of edge contrast can recreate. Sharpening fixes softness from resizing and compression, not from a missed focus.

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