GIMP Uncovered: Understanding Images and Image Editing

A Tutorial by Akkana Peck

The majority of Linux users have probably tried editing their
photographs with the GNU Image Manipulation Program (GIMP), and
many are regular users. You may use GIMP on a regular basis, or
you may be just starting out: but do you really feel like you
understand the details?

In this tutorial, you'll get down and dirty with GIMP. No prior
GIMP experience is required: beginners who haven't done any image
editing at all are welcome. As we progress, I'll cover the hows
and whys of each operation: intermediate GIMP users who use the
application on a regular basis may find that they can work much
more effectively by understanding some of the background behind
GIMP's operation.

I'll start by covering some of the basics of photo manipulation.
I'll discuss details of the different image formats: when should you
use a JPEG, and when might it be better to use GIF? What's PNG good
for? What about TIFF, ICO and BMP? I'll also discuss resolution versus
pixel size, an area which causes a huge amount of confusion among
users. How big should you make your image if you want to print it?
What size should you use for web images, and what are some ways
you can make your web images smaller without making them look bad?
What are the differences between raster and vector formats, and
how can you move between them?

Next, I'll cover layers. Layers are the heart of any GIMP operation
beyond the basic photo crop, resize, scale, brightness and contrast
operations, and an understanding of layers can make a huge difference
to your image editing experience. For me, beginning to understand
layers was the point where I stopped feeling like I was fighting GIMP
and started to love it. Layers sound intimidating when you haven't
used them before, but anyone can learn the basics in a few minutes --
a few simple examples will illustrate why they're useful and how to
manage them.

I'll also cover selection: perhaps the most difficult, yet most
important, aspect to manipulating photos and other pre-existing
images. GIMP offers many different methods for selecting a part of an
image -- so many that it's very easy to get confused and wonder what
they all do and which one is most appropriate. I'll talk about which
selection methods are best in common circumstances, how they relate to
each other, and how to switch among them.

Finally, I'll introduce users to layer modes, an often ignored yet
very powerful way of combining several images to get all sorts of
interesting effects; and I'll discuss some of GIMP's useful built-in
filters and plug-ins.

Direct link to video