Sharpen an image

What sharpening can and can’t fix

Sharpening increases contrast along edges, so outlines, hair and text look more defined. It works well on photos that are slightly soft: a little out of focus, resized down, or taken through a phone lens on a dull day.

It can’t rescue a badly blurred photo. If a face is a smudge because the subject moved, the detail was never recorded, and pushing the sliders only adds halos and grain. Tools that claim to restore heavy blur are generating new detail with AI, which is a different thing from sharpening.

Start with Unsharp

Unsharp mask, the default, is what professional editors use. Despite the name, it sharpens. It has three controls:

• Amount (0 to 200, default 80): how strong the effect is.
• Radius (0.5 to 10, default 1.5): how wide the edges it enhances are. Small values bring out fine texture; larger values add punch to big shapes.
• Threshold (0 to 40): skips tiny differences, so smooth skin and clear sky don’t turn grainy. Try 3 to 8 for portraits.

The other methods

• Laplacian: a simple edge boost with no radius. Quick and crisp, but it amplifies noise.
• High-pass: sharpens broader detail. Useful for landscapes and architecture.
• Edge: the strongest outline effect. Good for line art and diagrams, and usually too harsh for faces.

Signs you have gone too far

Bright halos along dark edges, crunchy-looking skin and speckled skies are the giveaways. Zoom into a high-contrast edge, such as a dark hairline against a light wall, and back the amount off until the halo disappears. Sharpening is best done last, after any resizing, because shrinking an image softens it again.

Questions