# `aug_unsharp_mask` — Unsharp Mask

_Group_: **Augmentation** · _Binding_: `n4m.sklearn.UnsharpMask` · _C ABI_: `n4m_aug_unsharp_mask_*`

## Description

Random unsharp spectral mask.

### Parameters

| Name | Type | Default |
|------|------|---------|
| `amount_lo` | `float` | `0.1` |
| `amount_hi` | `float` | `0.5` |
| `sigma` | `float` | `1.0` |
| `kernel_width` | `int` | `11` |
| `rng` | `Optional[PCG64]` | `None` |
| `seed` | `int` | `0` |

## Explanations

### Bibliographic source

_Standard spectroscopic operator — see the nirs4all preprocessing / augmentation handbook and the cited literature within the binding docstring._

### Mathematical principle

Random unsharp spectral mask.

### Implementation

C ABI `n4m_aug_unsharp_mask_*` in libn4m (create / apply / destroy lifecycle), wrapped by `n4m.sklearn.UnsharpMask`. The same numerical kernel backs every language binding.

### Usage

```python
from n4m.sklearn import UnsharpMask
op = UnsharpMask()
X_transformed = op.fit_transform(X)
```

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_See also_: [methods index](index.md) · [interactive dashboard](../landing/dashboard.md)