Selections are extremely important tools for working with digital
images. They are a means for partitioning an image into two groups of
pixels: those we want to work on and those we do not. Selections
allow the selective application of enhancements, functions,
filters, and plug-ins to specific target regions of an image.
Furthermore, selections are essential tools for compositing image
material from several sources into a single image. This is core to
collage and photo montage, two subjects developed in detail in
This chapter covers the selection tools in the GIMP. However, the
material presented here is really only half the story on the subject
of selections. The other half is presented in Chapter
which covers masks. As described there, selections and masks are
really just two implementations of the same principle. They both
result in a separation of subject from background. They arrive at
this result, however, using different and very complementary methods.
You really need both to get the best selection results.
Selections are the scalpel of the image manipulator's toolbox, and you
will use them a lot. Because selections can easily be the most
time-consuming and frustrating part of a project, it is important to
know how to use the selection tools artfully and effectively. This
chapter explains how each selection tool works, and it presents the
array of GIMP functions that are directly related to selections.
Furthermore, the conditions for which each selection tool is most
effective are described, and each tool is rated against the others for
Before launching into the descriptions of the various selection tools,
it is worthwhile to mention where selections fit into the structure of
images. The relationship of pixels, channels, layers, and images was
described in Section
2.2. Where, then, do
selections fit in? A selection can be seen in the image window--does
that mean it is part of the image? The answer to these questions
won't be fully given until Chapter
4, which covers masks.
However, for now it suffices to know that selections are special
channels, independent of the image layers, and whose selective effects
apply only to the active layer.