The title of this book, Grokking the GIMP, is drawn from Robert
A. Heinlein's classic science fiction novel Stranger in a Strange
Land. His story is about Valentine Michael Smith, the only survivor
of the first human expedition to Mars and raised from infancy by
Martians. The rescue mission arrives twenty years later to bring a
young man knowing nothing of his own kind back to earth. The story
recounts his repatriation and his adventures as he comes to grok
the human race and his place in it. Grok, a word he often uses, is
the Martian word meaning ``to drink,'' but which also serves as a
quasi-religious metaphor in the Martian culture for having a profound
appreciation and understanding for something.
Heinlein's book, published in 1961, drew immediate acclaim in the
science-fiction world, and the story became a part of the iconoclastic
cultural sentiment of the 60s in the United States. Today, the word
grok is a part of the U.S. computer hacker vocabulary, and its definition
can be found in The New Hacker's Dictionary (see
So, do you want to grok the GIMP? When I first came across it in
1996, I did. I was writing an article and had some photographs of
poor quality I wanted to touch up and enhance before including them.
I had heard about the GIMP so I downloaded it from the Internet and
compiled it. When I ran the program, it popped up a small toolbox.
Without too much trouble, I discovered how to open image files and
access the image menu containing all the GIMP functions and filters.
Wow! It looked very cool...and powerful! But, I didn't have
a clue how to use it to solve my photo problems.
I didn't know which functions to use and I didn't even really know
what was wrong with my photos. I just knew they looked flat and
washed out. I wanted them to look better, and that's what got me
interested in the GIMP. I felt compelled to learn about it!
I started to look for help. I searched the Web, checked out books
from the library, and little by little discovered useful things about
the digital touchup and enhancement of photos. It was a slow and
frustrating process, and it seemed like there was no unified,
conceptual treatment of what I wanted to learn.
The most annoying thing was that almost every book I picked up was
full of tips and tricks. Tips and tricks? I felt like I was getting
advice on betting the ponies. I didn't want tricks; I wanted the
ideas. What is photo touchup and enhancement? Where's the
beef? How could I work on my photos if I didn't understand the basic
concepts? Moreover, I wanted to learn the practical techniques used
by the master artisans of digital image manipulation. Out of the
hundreds of functions and filters in the GIMP, which were the right
ones to use, and why?
After a lot of detective work and filling in the blanks myself I
finally felt I was beginning to grok what the touchup and enhancement
of digital images was about. What's more, I was getting to know the
GIMP tools more intimately. To share what I had learned, I wrote a
tutorial called Photo Touchup and Enhancement with the GIMP and
put it out on the Internet (see
That's the story of this book's beginnings and that explains the
rationale for its underlying approach and philosophy. Working with
digital images requires some understanding of what needs to be done.
It's not a ``choose the right tool, one click, and you're done''
subject. Most books on digital image manipulation would have you
believe the contrary...and perhaps they're right. However, that
is not what this book is about. It is not about tips and tricks, and
it's not a collection of recipes for solving someone's favorite image
manipulation problems. It is first about understanding image
manipulation concepts, second about knowing which GIMP tools are most
effective, and third about the savvy use of these tools.
Many factors have contributed to the style and content of the material
presented in this book. My educational training in signal processing,
my professional work in various areas of imaging and image processing,
the research I've done on colorspaces and image manipulation, and lots
of experimentation with the GIMP. The result is a book that covers
many areas of working with digital images, including touchup and
enhancement, compositing, 3D rendering, and the presentation of
graphics on the World Wide Web. This book also gives a unified and
in-depth introduction to layers, selections, masks, colorspaces, and
the use of blending modes.
This book is released under an Open Publication license. Please read
the license agreement carefully. In a nutshell the license permits
the book to be redistributed freely in all electronic forms including
CD and for commercial profit. It may not, however, be commercially
printed and distributed in paper form without permission from the
author and publisher. It can be printed for personal use and
for non-commercial distribution. Modified versions of the book must
also adhere to the licensing agreement.
Now, let's learn the GIMP, and, as Valentine Michael Smith might have
said, ``May you grok it in fullness!''
October 26, 1999