Sharpen node

This documentation is for version 4.0 of Sharpen.


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


Input Description Optional
Source   No
Mask   Yes


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: Quasi-Gaussian filter (0-order recursive Deriche filter, faster) - IIR (infinite support / impulsional response).
Gaussian: Gaussian filter (Van Vliet recursive Gaussian filter, more isotropic, slower) - IIR (infinite support / impulsional response).
Box: Box filter - FIR (finite support / impulsional response).
Triangle: Triangle/tent filter - FIR (finite support / impulsional response).
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.