Algorithms are chosen via the Algorithms menu, and are executed immediately. Algorithms are cumulative, in that if you run an algorithm on an image, and then run a second algorithm, the second algorithm operates on the modified image produced by the first algorithm. And so on. Also, it should be noted that the algorithms operate on 24-bit images. When you select this command, a dialog box is opened up to request the value for ' n '.
Larger values blur the image to a greater extent.
Values above '15' aren't particularly recommended. Runs a convolution using a pair of convolutions, one which detects horizontal edges, and one which detects vertical edges. It is only done for pixels that have the 3x3 mask fully contained within the image, to avoid pesky edge conditions. You'll get red edges when there are edges in the red plane, yellow edges when there are edges in the red and green planes, and so on. Then, the results will also be grey.