# Sharpen node¶

*This documentation is for version 4.0 of Sharpen.*

## Description¶

Sharpen the input stream by enhancing its Laplacian.

The effects adds the Laplacian (as computed by the Laplacian plugin) times the ‘Amount’ parameter to the input stream.

Uses the ‘vanvliet’ and ‘deriche’ functions from the CImg library.

CImg is a free, open-source library distributed under the CeCILL-C (close to the GNU LGPL) or CeCILL (compatible with the GNU GPL) licenses. It can be used in commercial applications (see http://cimg.eu).

## Inputs¶

Input | Description | Optional |
---|---|---|

Source | No | |

Mask | Yes |

## Controls¶

Parameter / script name | Type | Default | Function |
---|---|---|---|

Amount / `amount` |
Double | 1 | Amount of sharpening to apply. |

Size / `size` |
Double | x: 3 y: 3 | Size (diameter) of the filter kernel, in pixel units (>=0). The standard deviation of the corresponding Gaussian is size/2.4. No filter is applied if size < 1.2. |

Uniform / `uniform` |
Boolean | Off | Apply the same amount of blur on X and Y. |

Filter / `filter` |
Choice | Gaussian | Bluring filter. The quasi-Gaussian filter should be appropriate in most cases. The Gaussian filter is more isotropic (its impulse response has rotational symmetry), but slower.
Quasi-Gaussian (quasigaussian): Quasi-Gaussian filter (0-order recursive Deriche filter, faster) - IIR (infinite support / impulsional response).Gaussian (gaussian): Gaussian filter (Van Vliet recursive Gaussian filter, more isotropic, slower) - IIR (infinite support / impulsional response).Box (box): Box filter - FIR (finite support / impulsional response).Triangle (triangle): Triangle/tent filter - FIR (finite support / impulsional response).Quadratic (quadratic): Quadratic filter - FIR (finite support / impulsional response). |

(Un)premult / `premult` |
Boolean | Off | Divide the image by the alpha channel before processing, and re-multiply it afterwards. Use if the input images are premultiplied. |

Invert Mask / `maskInvert` |
Boolean | Off | When checked, the effect is fully applied where the mask is 0. |

Mix / `mix` |
Double | 1 | Mix factor between the original and the transformed image. |