The FXScript Reference

Blurs all channels of an image buffer including the alpha channel. The source (srcImage) and destination(destImage) image buffers must be different or visual feedback will occur.

This function's aspect value refers to the pixel aspect ratio of the output image and will skew results accordingly. In most cases, this should match AspectOf, but other values can be used to produce much more extreme blur distortions.

Values below 1 will skew the resulting blur vertically, or horizontally, values greater than 1 distort horizontally. Vertical distortions seem capable of more extreme distortion, high values appear to stop having an effect at about 5.