Question 1

How does the image sharpener work?

Accepted Answer

It uses the classic Unsharp Mask algorithm. The image is lightly blurred, the difference between the original and blurred version is computed, and that difference is multiplied by an amount and added back to the original. This accentuates edges and high-frequency detail, making the photo look crisper.

Question 2

Can it fix a really blurry photo?

Accepted Answer

It works well on slightly soft or out-of-focus images by enhancing local contrast. Severely blurred photos cannot be fully recovered in a browser because true deconvolution needs heavy compute, but raising the Amount and Radius can recover a lot of perceived sharpness.

Question 3

Is my image uploaded anywhere?

Accepted Answer

No. All processing happens entirely in your browser using Canvas and JavaScript. Your images never leave your device.

Question 4

What are good settings to start with?

Accepted Answer

For mild softness use Amount 50, Radius 1, Threshold 0. For portraits with skin use Amount 80, Radius 1, Threshold 4 to avoid sharpening noise. For text or screenshots use Amount 150, Radius 0.5, Threshold 0.