# Smoothing¶

Widgets -> Processing -> Smoothing

This widget provides simple Gaussian smoothing.

Sigma is the standard deviation of the Gaussian used in the convolution in mm. Note that if the voxel size of the data is different in different dimensions then the smoothing in voxels will be non-isotropic. For example if you select 1mm as sigma with data that consists of 5mm slabs in the Z direction with 1mm resolution in the XY directions, then very little smoothing will be evident in the Z direction, but the XY slices will be visible smoothed.