Question 1

Is the photo sharpener really free?

Accepted Answer

Yes. Local Sharpen runs on your own device, so it costs us nothing per image and needs no account. Limits come from your browser and device memory; we accept files up to 30 MB and 40 megapixels.

Question 2

Is this AI sharpening?

Accepted Answer

No. It uses an unsharp mask, a classic non-generative technique: it compares each pixel’s brightness with a blurred copy and increases the difference along edges. It never invents letters, faces or textures, but it does change pixel values.

Question 3

Can it fix a badly blurred photo?

Accepted Answer

No sharpening tool can recover detail that was never captured. Sharpening helps photos that are slightly soft. Strong motion blur or a missed focus usually needs a retake.

Question 4

Will it keep my PNG transparent?

Accepted Answer

Yes. Only brightness is sharpened; the alpha channel is copied unchanged, so transparent and semi-transparent pixels stay as they were.

Question 5

Why does my sharpened photo look crunchy?

Accepted Answer

Too much amount or too large a radius exaggerates noise, compression artifacts and halos. Start with the Light or Medium preset, keep the radius around 0.5–1.0 px, and raise the threshold to protect smooth areas such as skin and sky.

Question 6

Does it work on iPhone photos?

Accepted Answer

Yes for JPG and PNG. HEIC files must be exported as JPG first. On iPhone you can also try Photos → Edit → Sharpness, which is free and built in.

Setting	What it does	Start with
Amount	How much edge contrast is added	50–90% for photos, up to 150% for text and line art
Radius	The size of the edges being sharpened	0.5–1.0 px for most photos; 1.2–1.5 px for large prints
Threshold	Skips tiny differences so smooth areas stay smooth	2–4 for most photos; 6–10 for portraits with skin

Setting	What it does	Start with
Amount	How much edge contrast is added	50–90% for photos, up to 150% for text and line art
Radius	The size of the edges being sharpened	0.5–1.0 px for most photos; 1.2–1.5 px for large prints
Threshold	Skips tiny differences so smooth areas stay smooth	2–4 for most photos; 6–10 for portraits with skin

Photo Sharpener

What sharpening does — and what it can’t do

Recommended settings

How to check that nothing is uploaded

Local Sharpen facts

Frequently asked questions