User Guide
GNU Image Manipulation Program
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15.1.1 Preview
Most filters have a Preview where changes in the image are displayed, in real time (if the ‘Preview’ option is checked), before
being applied to the image.
Figure 15.1: Preview submenu
Right clicking on the Preview window opens a submenu which lets you set the Style and the Size of checks representing
transparency.
15.2 Blur Filters
15.2.1 Introduction
Figure 15.2: Original for demo
This is a set of filters that blur images, or parts of them, in various ways. If there is a selection, only the selected parts of an
image will be blurred. There may, however, be some leakage of colors from the unblurred area into the blurred area. To help you
pick the one you want, we will illustrate what each does when applied to the image shown at right. These are, of course, only
examples: most of the filters have parameter settings that allow you to vary the magnitude or type of blurring.
Figure 15.3: Gaussian blur (radius 10)
The most broadly useful of these is the Gaussian blur. (Don’t let the word "Gaussian" throw you: this filter makes an image
blurry in the most basic way.) It has an efficient implementation that allows it to create a very blurry blur in a relatively short
time.