Gaussian filtering is a smoothing or blurring process that convolutes the image with a Gaussian function:

G(x,y)=\frac 1{2\pi \sigma ^2}e^{\frac{x^2+y^2}{2\sigma ^2}}

The output is similar to a weighted average of the neighboring pixels, with the weights in the center larger than the weights near the boundaries. To use this function,

select Image: Spatial Filters: Gaussian from the Origin menu.

For more specific information on this function, see documentation provided for the X-Function imgGaussian in the Origin X-Function reference file. This can be accessed from the Command Window by typing

help imgGaussian