User Guide

GNU Image Manipulation Program
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Blur Radius The bigger the radius, the more marked is the blur. By selecting Horizontal and Vertical, you can make the
horizontal and vertical borders tileable.
Blur Type IIR: for photographic or scanned images.
RLE: for computer-generated images.
15.3 Color filters
15.3.1 Introduction
The Color filters group contains several filters to modify colors in an image, a layer or a selection. You can find filters to compose,
decompose, uncolor colors, and many other effects.
15.3.2 Adjust FG-BG
15.3.2.1 Overview
Figure 15.20: Applying example for the ‘Adjust FG-BG’ filter
(a) Original image (b) Filter Adjust FG-BG applied
You can find this filter through Filters → Colors → Map → Adjust FG-BG.
Adjust FG-BG belongs to color map filters which make connection between a color source and an image. Here, image pixels hav-
ing ForeGround color will turn to black while pixels having BackGround color will turn to white. Other colors are interpolated.
There will be no change if FG is black and BG is white.
Note that this filter is just a special case of the Map Color Range filter with its default colors: source colors are foreground and
background color, destination colors are black and white.
Caution
This filter does not work as expected, if the values of foreground and background color are the same for some color
channel (red, green, or blue).
Even worse: the filter will happily accept your colors without displaying a warning or error message.