IMAGE PROCESSING REFERENCE
Explore the pixel-level unsharp-mask calculation used by FileTools and see how sigma and threshold affect sharpening.
Difference: 15
Threshold exceeded: yes
Output channel: 175
The calculator models the channel step after the blurred image has been produced. The actual blur is image-dependent and is controlled by sigma.
The browser slider passes its value as the sigma parameter to Rust's image unsharp-mask operation. FileTools uses a threshold of 1, so a channel difference must exceed 1 before the sharpening step changes it.
diff = original - blurred if |diff| > 1: output = clamp(original + diff, 0, 255) else: output = original| UI strength | Rust sigma | Threshold |
|---|---|---|
| 0 | 0 | 1 |
| 0.5 | 0.5 | 1 |
| 1 | 1 | 1 |
| 2 | 2 | 1 |
| 3 | 3 | 1 |
| 4 | 4 | 1 |
| 5 | 5 | 1 |
| 7.5 | 7.5 | 1 |
| 10 | 10 | 1 |
The sigma value controls how strongly the image is blurred before the difference is calculated. It is not a percentage of sharpness, and other image editors may expose completely different controls.
Apply the same browser-based operation to a real image with the free image sharpening tool.