Maybe it would help to have a general explanation of the principle behind
The basic idea of the Unsharp Mask is to enhance the difference between the
and a blurred version of it. The algorithm first blurs the image, then
calculates the difference
between the original image and the blurred version, and then alters the
original image by
moving each pixel farther away from its blurred value.
The convolution is simply a way of blurring the image. There are countless
doing a blur -- the filter is using a rather crude approximation of a
Gaussian blur, which
is the most commonly used blurring algorithm.
Gimp-developer mailing list