GIMP Bible E-Book

Jason van Gumster

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Bible
• Sprache: Englisch

Seitenzahl: 1216

Veröffentlichungsjahr: 2011

Beschreibung

The ultimate reference and guide to the GNU image manipulation program GIMP is a free, Photoshop-like image manipulation program, and as its use grows, so does the demand for detailed instruction on how to get the very most out of it. GIMP Bible is the most comprehensive and current independent GIMP reference available that goes beyond official documentation. If you're a digital artist or photographer, the step-by-step explanations in this authoritative guide show you how to power-use GIMP throughout a production pipeline. Topics include understanding the GIMP interface and how to work with it, how to use all of GIMP's tools to create high-quality images, GIMP's default filters and plug-ins, advanced techniques for customization with Python and Scheme scripting, and much more. * GIMP (GNU Image Manipulation Program) is a free graphics editor that runs on Linux, Windows, or Macs; it is used to process digital graphics and photographs including creating graphics and logos, resizing and cropping photos, altering colors, combining images, creating basic GIF animated images, and more * Whether you're a digital artist, professional photographer, or beginner, this detailed how-to shows you best practices, valuable techniques, and helpful tips for getting the most out of GIMP for your projects * Topics include the GIMP interface and how to work with it, in-depth description of GIMP's tools and how to use them to create high-quality images, a comprehensive reference for all of GIMP's default filters and common plug-ins, and advanced customization with Python and Scheme scripting Get the most out of this free image editing tool for your production pipeline with the GIMP Bible.

Leseprobe

Table of Contents

Title Page

Copyright

Dedication

About the Authors

About the Technical Editor

Credits

Acknowledgments

Introduction

What to Expect

Conventions Used in This Book

Contact Information

Part I: Meet GIMP

Chapter 1: What Is GIMP?

Knowing What GIMP Can and Cannot Do

Working with GIMP's Interface

Setting Preferences

Customizing Keyboard Shortcuts

Summary

Chapter 2: Thinking Digitally

Digital Images vs. Traditional Photographs

Raster Graphics vs. Vector Graphics

Resolution and Image Size

Color Depth

Color Spaces and Color Modes

Compression

Summary

Part II: Getting Started

Chapter 3: Working with Files

Opening Files

Working in the Image Window

Copying and Pasting

Taking Advantage of Undo

Saving Files

Summary

Chapter 4: A Brief Overview of GIMP's Tools

The View Menu

Selection Tools

Image Tools

Paint Tools

Color Tools

Summary

Chapter 5: Taking Advantage of Paths

The Advantages of Paths: Get Some Vector in Your Raster

Creating Paths

Managing Paths

Using Paths

Summary

Chapter 6: Working with Layers and Masks

Managing Layers

Manipulating Layers

Blending Modes

Using Layer Masks

Summary

Chapter 7: Using Channels

Understanding Channels

Using Channels

Summary

Part III: Manipulating Images

Chapter 8: Transforming Images

Adjustments Available in the Image and Layer Menus

Using the Image Tools

Summary

Chapter 9: Adjusting Colors

Using the Color Menu

Exporting Color Separations with the Separate+ Plug-in

Summary

Chapter 10: Working with Text

Uses for Text in Images

Adding and Editing Text

Working with Text Layers

Summary

Chapter 11: Painting in GIMP

Working with Brushes

Drawing Calligraphic Lines with the Ink Tool

Working with Gradients

Creating Pattern Fills

Summary

Chapter 12: Enhancing Photos

Traditional Photographer Tools

Using Cloning and Healing to Fix Problem Areas

Using the Exposure Blend Plug-in

Summary

Part IV: Exploring Filters and Effects

Chapter 13: Implementing Blur, Enhancement, and Distortion Filters

Common Features among Filters

Using the Blur Filters

Enhance Filters

Distortion Filters

Summary

Chapter 14: Using Image Creation Filters

Light and Shadow Filters

Noise Filters

Render Filters

Summary

Chapter 15: Using Compositing Filters

Working with Edge-Detect Filters

Using the Filters in the Generic Menu

Using the Combine Filters

Taking Advantage of Mapping Filters

Summary

Chapter 16: Enhancing Images with Artistic Filters

Artistic Filters

Decor Filters

Summary

Chapter 17: Working with Specialized Filters

Web Filters

Animation Filters

Alpha to Logo

Summary

Chapter 18: Batch Processing with Automating Filters

Batch Processing Multiple Files

Automating Tasks with GAP's Filtermacro

Filter All Layers

Summary

Chapter 19: Using GIMP Animation Package

Using Still Image Sequences and Layers for Animation

Convenience Features to Improve Workflow

Creating a Storyboard

Summary

Chapter 20: Working with Video-Specific Functions in GIMP

Playing Back Video

Encoding Video

Extracting Frames from a Video File

Summary

Part V: Advanced Topics

Chapter 21: Finding and Installing Plug-ins

The GIMP Plugin Registry

Installing Plug-ins

A Few Plug-ins Worth Mentioning

Summary

Chapter 22: Creating Custom Effects with Scripting

Multi-Lingual GIMP: Scripting Languages GIMP Understands

Using the Scripting Console

Writing a Custom Script for GIMP

Summary

Part VI: Appendices

Appendix A: Downloading and Installing GIMP

Installing GIMP on Linux

Installing GIMP on Windows

Installing GIMP on Apple Macintosh

Appendix B: Setting Up External Input Devices

Acquiring Images with a Scanner

Printing Images

Configuring a Drawing Tablet

Appendix C: Customizing GIMP

Changing the Splash Image

Using a Different Theme

Appendix D: Additional Resources

On the Web

Internet Relay Chat

Appendix E: What's on the Web Site

How the Site Is Organized

Getting the Most out of the Site

Index

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GIMP Bible

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To my mother, who once made the mistake of telling me I could do anything I set my mind to do…only to have me terrorize her by trying to do everything.

—Jason van Gumster

This book is dedicated to my son, Dylan James.

—Robert Shimonski

About the Authors

Jason van Gumster got into animation when he realized that he wanted to create movies… but that actors are generally intolerant of having pianos dropped on them. Using open source tools at nearly every step in production, Jason has produced animations and visual effects for television, film, and video games in his official capacity as a “Production Monkey” for Hand Turkey Studios, the company he helped start in 2005. He uses GIMP and the GIMP Animation Package on a daily basis for a variety of tasks ranging from creating graphics for the Web and television to drawing storyboards and creating images for both 3D and hand-drawn animations. Also the author of Blender for Dummies, Jason has given numerous live workshops and demonstrations on Blender internationally. Combining a unique educational background in animation and computer engineering with a penchant for the ridiculous, he strives to refine both the technical and creative aspects of production by taking on (and successfully completing) crazy projects like producing a 5-minute 3D animated short in a mere 48 hours with an international team communicating via the Internet. Based in Richmond, Virginia, Jason can often be found in cafés and diners drawing, espousing the virtues of open source software, or catching confused looks from strangers as he contorts his body to better visualize a scene he's animating.

Robert J. Shimonski is an expert digital media and technology consultant living in New York. Rob is also an author, and a regular contributor of tutorials and articles on digital editing, production, and development.

Having spent the past decade working with large, medium, and small companies as a technical consultant, Rob has helped develop digital art packages for many professional clients and businesses.

Rob has been working with GIMP for many years and has created graphics for corporate web sites, TV commercials, and professional magazines. Having worked with the many open source tools, Rob relies on GIMP for most of his graphics work.

Rob can be found online at www.shimonski.com.

About the Technical Editor

John Karnay is a published author and editor with over a dozen works to his credit. He has been writing and editing in the fields of technology, fiction, comic books, computer software, music, and video games for over 15 years. John is a computer software, audio engineering, graphic design, networking and IT specialist who has been working with and deploying Microsoft-, Apple-, and open source-based technologies for over 15 years. He also specializes in Spanish-to-English translation. John currently works in the video game industry as a producer, content writer and quality assurance manager and has over 30 game titles to his credit.

John resides in Jackson Heights, New York and spends his free time with his daughter Aurora and with his loving wife and partner, illustrator Gloria Rios.

Credits

Executive Editor

Carol Long

Project Editor

Sydney Jones

Technical Editor

John Karnay

Production Editor

Daniel Scribner

Copy Editor

Kim Cofer

Editorial Director

Robyn B. Siesky

Editorial Manager

Mary Beth Wakefield

Associate Director of Marketing

David Mayhew

Production Manager

Tim Tate

Vice President and Executive Group Publisher

Richard Swadley

Vice President and Executive Publisher

Barry Pruett

Associate Publisher

Jim Minatel

Project Coordinator, Cover

Lynsey Stanford

Proofreader

Heather Dweller

Indexer

Johnna VanHoose Dinse

Cover Illustration

Joyce Haughey

Cover Designer

Michael E. Trent

Acknowledgments

First (and most important) thanks go to the surprisingly small group of dedicated developers who voluntarily spend their free time coding GIMP. Most people don't realize that a program of GIMP's complexity is updated and maintained by only a handful of developers whose primary motivation is the fact that they enjoy doing it. Your patience and help with my questions and misplaced bug reports are sincerely appreciated. You are not and cannot be thanked enough.

Thanks, also, to the entire team at Wiley. Were it not for this talented group of professionals (and large quantities of coffee), this book would never have been produced. I'd especially like to acknowledge my project editor of unparalleled patience and tireless energy, Sydney Jones. I'd also like to thank Rob Shimonski not only for working as this book's initial technical editor, but also for stepping up and agreeing to write a portion of the book on incredibly short notice. It has been a pleasure to work with both of you. — Jason van Gumster

A book takes a lot of work to create and requires a very large team effort. I would like to thank the Wiley production team for all of their hard work. I would first like to thank my co-author Jason, who is truly a GIMP wizard. Special thanks goes out to Sydney for her untiring dedication to this project. I would also like to thank technical editor Johnny for keeping things on track. Lastly, I would like to thank Carol, who got me started on the project and kept everything locked on. — Robert Shimonski

Introduction

Thanks for picking up GIMP Bible, which I hope is the most comprehensive and up-to-date book on this very cool piece of Free Software. Whether you're a hobbyist interested in a free image editor, or a seasoned professional curious about what “that GIMP thing” is capable of, this book is designed to meet your needs and give you the information you're looking for. The idea is to cover everything that GIMP can do while also involving topics related to computer graphics in general. The primary purpose of this book is to show you how to be really productive with a program this complex. If you're anything like me, the more cool things you can make and the faster you can make them, the more fun you're having. And really, it's all about having fun. This is especially true for a program like GIMP, which is developed by volunteers all over the world, in their free time, because they really enjoy it.

That said, no piece of software is perfect and everyone has an opinion, myself included. Throughout the book, I may periodically voice my opinion about a feature in GIMP or a topic in computer graphics. However, when I do that, I try to make it a point to qualify that opinion and couple it with a relevant tip, trick, or workaround that's actually useful to you.

What to Expect

Unlike a lot of other books on the topic, GIMP Bible covers more than just the standard release of GIMP. GIMP's primary function is that of an image editor and GIMP is typically used a lot in photo editing. However, it's capable of quite a bit more, especially if you factor in the bevy of extensions and plug-ins that are available. For that reason, I also cover a variety of these very helpful plug-ins that are critical for digital artists who work in print, digital painting, video, and animation.

Another very important thing to note is that this book's goal is to be as up-to-date as possible, with a focus on the most recent features available. GIMP Bible is targeted to cover the features in the stable GIMP 2.8 release. Consequentially, much of this book was written using the GIMP 2.7 development series (the way GIMP versions work, odd decimals – 2.3, 2.5, 2.7 – are development versions and even decimals – 2.6, 2.8 – are stable). That being the case, there may be some minor inconsistencies between what you see on the screen and what you read in the text or see in the figures. The good news, however, is that by and large GIMP is still GIMP. What I mean is that while there may be some differences in how things look in GIMP, they should still work the same. A button may be moved or renamed, but it still performs the same function. Furthermore, to alleviate these issues, I will be diligently posting updates, errata, and tutorials to this book's companion website, www.wiley.com/go/GIMPBible.

Who This Book Is For

Because GIMP Bible is designed as a reference suitable for both beginners and experts in producing computer graphics, it doesn't presume to know your level of understanding of the field. Most terms and concepts related to computer graphics are explained in the text. That said, we've written this book with the assumption that you have at least a basic understanding of how your computer works. You should know how to start programs, open files, and install software on your operating system. The last of these is particularly important if you need to install some of the plug-ins and extensions covered within this book. On the hardware side of things, you should also be able to use peripherals like a mouse or drawing pad and understand the difference between system memory (RAM) and storage memory (hard drive or external media like USB sticks).

What This Book Contains

Looking through this book's table of contents, you can get a good idea of all of the concepts and topics that are covered. GIMP Bible is organized into seven parts, The following is a description of each one:

Part I: Meet GIMP — This part serves as your first introduction to GIMP, providing a bit of its history and a first taste of the interface. The second chapter in this part should be particularly useful for complete beginners go computer graphics because it provides an introduction to many of the concepts and a lot of the terminology used throughout the rest of the book.Part II: Getting Started — This next part of the book really gets into the details of GIMP's interface and the features it provides. It starts with coverage of how GIMP handles files, and works forward through adjusting the image window. From there, the chapters in this part cover topics such as creating selections and taking full advantage of those selections with GIMP's Paths, Layers, and Channels dialogs.Part III: Manipulating Images — The focus of the chapters in this part is the application of GIMP's tools to manipulate existing images and create custom graphics. It starts with moving, rotating, and deforming elements of your images and continues to cover how much you can modify your image by simply modifying its colors. The final three chapters in this part really get into adding new content to your images in the form of text, paint strokes, and photo enhancement tools.Part IV: Exploring Filters and Effects — One of the most prominent features of GIMP is its incredibly wide variety of available filters. Filters are sets of processing steps that can be applied to your image in a single shot. Their effects range from barely perceivable and subtle to a complete overhaul of the appearance of your image. The chapters in this part cover every one of the filters that ship with GIMP, as well as a few useful ones that don't.Part V: Advanced Topics — Part of the beauty of GIMP is its extensibility. Anyone with a computer and a little bit of programming knowledge can add new features and functionality to GIMP in the form of extensions and plug-ins. Throughout the rest of the book, I cover some of these “third-party” extensions that don't come with GIMP by default. The chapters in this part cover the installation of these additions and then go into how you can easily write your own custom extensions to help improve your efficiency while working.Part VI: Appendices—Most of GIMP Bible is focused on creating computer art and graphics with GIMP. In order to use GIMP for that purpose, however, there are some technical steps that you may need to perform to get GIMP installed on your computer and to get your hardware playing nicely with it. The appendices provide you with those steps. They also cover supplemental information such as ways to customize the appearance of GIMP and additional resources online where you can learn more about GIMP, including this book's companion website, wiley.com/go/GIMPBible.com.

Conventions Used in This Book

As with any book on a technical topic, especially ones that deal with computer software, there are specialized methods and terminologies that specifically relate to the software or the field being covered. To deal with that, this book employs a few standards and conventions:

Terminology

Seeing as how this book is targeted at raw beginners as well as seasoned professionals (salty experts?) in computer graphics, I make it a point to define terminology and jargon specific to the field or unique to GIMP. You'll be able to notice this because defined words, like megapixel, will be italicized. The definition will immediately follow. If you run across a non-italicized word that you don't recognize, have a look in the index of this book and see where else it's used. That should give you enough context to figure it out on your own. And if that still doesn't work for you, send me an email (given in the “Contact Information” section later) and I'll do my best to clear things up for you.

Commands, Options, and Menus

Throughout this book I continually make reference to various commands, options, and menus in GIMP's interface. For many commands in GIMP, there's often more than one way to invoke them. So when I first give you a command, I'll also provide each of the ways to perform it, including a keyboard shortcut if one exists by default. If I reference a command more than once, then I typically just provide the fastest way to invoke that command.

Often commands are invoked by navigating a menu. In these cases, I use arrows to indicate drilling down through submenus to the final menu item, like Filters ⇒ Map ⇒ Make Seamless. Also, for both menu items and options that are in GIMP's interface, I use title case when referring to them. That is, I'll capitalize the first letter in each main word of the option or menu item, like Use Color from Gradient. Now, this choice may differ from the way it appears in GIMP, but capitalization in GIMP's interface is a bit inconsistent in parts. Because I use uppercase letters in this book in a consistent manner, you'll at least know what words to look for when going to GIMP's interface.

You may also notice that I may explicitly tell you whether to left-click, right-click, or (on occasion) middle-click. This is because working efficiently in GIMP requires that you have at least a two-button mouse. There's a lot of functionality in dialogs like the Layers and Channels dialogs that is most quickly accessed with a right-click. There are occasions in the book where I simply say click and don't stipulate which mouse button to press. In these cases any mouse button should do, but it's best to assume left-click.

Using GIMP on Multiple Platforms

GIMP runs on every major computing platform, or operating system on modern computers, including Linux, Unix, Mac OS X, and Windows. The cool thing is that regardless of the platform, GIMP typically looks and behaves the same. That said, there are a few things to bear in mind. For instance, Mac users may be used to pressing the Command key for operations like copy and paste. However, GIMP's current default is to use the Ctrl key across all platforms. Also, since printing, scanning, and screen capture subsystems vary from one operating system to another, there are minor differences in the way GIMP accesses them. These little inconsistencies across platforms can be a slight source of frustration for users who are used to working a certain way. For that reason, whenever one of these differences pops up, I make sure to point out how GIMP handles them on each platform. These differences are usually minor, though, so GIMP should look the same on all platforms. Since my preferred work environment (and GIMP's primary development) is in Linux, most of the screenshots in this book are taken from that platform. However, for the relatively few places where there are differences on Mac OS X or Windows, I do have platform-specific screenshots.

Another thing to note is that I occasionally need to refer to a location on your computer's hard drive. Since most operating systems do it this way, I notate the path using the standard forward-slash notation, like so: /usr/share/gimp. For those of you using Windows, you simply need to translate to using back-slashes and drive letters. And for you Unix folks, the things you call directories and sub-directories (such as usr or share in the previous example), I refer to as folders and sub-folders. How's that for compromise?

Versions and Actively Developed Software

Since this book covers plug-ins that don't ship with the official release of GIMP — plug-ins that you may have to download and install yourself — I've made it a point to try to use the most current stable version of each of these plug-ins. This is particularly true for larger plug-ins like G'MIC and Liquid Rescale, as well as extensions such as the GIMP Animation Package. Where it's helpful, I mention the version of the plug-in and how it may differ from previous versions. The companion website for this book (wiley.com/go/GIMPBible.com) also has links to the most current versions of any of these plug-ins, and provides any tips you may need to follow in order to get them installed.

And as I mentioned earlier, GIMP Bible was written while GIMP was under heavy development for the 2.8 series. It was an interesting challenge, but my hope is that doing this gives you the most thorough look at the new GIMP so you can take full advantage of all of the goodies the developers have packed into it for us. Where it's relevant, I'll mention how the behavior of GIMP 2.7/2.8 differs from the previous stable version and explain the benefits of the new behavior.

Features Used in This book

A common feature in Wiley's Bible series of books is the very useful icons. GIMP Bible uses these icons to highlight discussion topics and provide you with quick tips, warnings, and workarounds that relate to those topics. They're there to help and they can often give you a really cool or unexpected way to use a tool or perform a particular task. Skip them if you want, but you'll be missing out on the really good, juicy bits of information. In this book, you'll run across the following icons:

Warning

The Warning feature is probably one of the most important ones to look out for. The text by this icon gives you warnings of potential situations that may cause you to crash GIMP, or worse, lose data. The good news is that most of the time there's a workaround for these scenarios and the text next to the Warning icon provides you with it.

Note

Note features indicate bits of information that are handy to remember while you work. They provide additional information on how a particular feature or tool works. That information can, in turn, illuminate why that feature works in a particular way. If you want to get the most out of using GIMP, keep an eye out for these icons.

Tip

Tip features are the fun features. They give you hints at how to take advantage of GIMP or use it more efficiently. Also, in situations where a feature doesn't work as you might expect it to, Tip icons explain how you can bend that feature to your will.

Contact Information

This book was not written in a vacuum. A key tenet of the Free Software philosophy is the open exchange of information. Jason welcomes any reader's questions, suggestions, complaints, and (hopefully) the occasional compliment. The most effective way is through the blog and supplemental tutorials on this book's companion website at wiley.com/go/GIMPBible.com. This way if there's anyone else out there who has the same question you do, everyone can benefit from the answer. Of course, you can also reach me directly via email at [email protected]. While I will definitely read each and every email, because of the volume of email I receive, I cannot guarantee that I'll respond to all of them immediately. I do, however, promise to reply to any email that's sent to me. It just might take a while.

I only have one request: please limit your emails to content that relates specifically to GIMP Bible. If you have a bug report or feature suggestion for GIMP itself, please use the GIMP developer email list or bug tracker. Since I'm not an active GIMP developer, these are much more effective channels for those kinds of discussions.

Alright, enough talk. It's time to get elbow-deep in GIMPy goodness!

Part I

Meet GIMP

In This Part

Chapter 1 What Is GIMP?

Chapter 2 Thinking Digitally

Chapter 1

What Is GIMP?

In This Chapter

Understanding GIMP's capabilities and limitationsBecoming familiar with GIMP's interfaceLooking at preferences and customization

GIMP, GIMP, GIMP… oh what a name for an image editing program! With a name that's an acronym for GNU Image Manipulation Program, GIMP is the foremost application for raster graphics in the Free Software world. It's used for a variety of tasks ranging from photo editing and digital painting to batch image processing and traditional-style animation. If you have any interest in creating digital images, chances are good that you've at least heard of GIMP and perhaps even tried using it.

Whether you're a digital artist on a budget, an aspiring student, or just someone who needs a graphics program with more advanced features than those found in the simple paint program that may have come with your computer, GIMP is well-suited to helping you turn your ideas into images. You can start with a digital photograph, artwork from a scanner, or work from a blank canvas and create complete graphics from scratch. It's a great tool for getting the job done.

GIMP was born as a university project for two developers, Peter Mattis and Spencer Kimball, to fill the need for an advanced image editing program in the Unix and Linux environments when none existed. It has since grown to be an extremely influential force in the Linux world. In fact, the toolkit that was used to create GIMP's interface has been extended and expanded to become the basis for one of Linux's most popular desktop environments, GNOME. But although GIMP is included by default on nearly all popular distributions of Linux, you don't have to be a Linux user to take advantage of it. GIMP is a truly multiplatform program also available to Microsoft's Windows and Apple's Mac OS X users.

Perhaps GIMP's most valuable feature is its free and open nature. Not only is GIMP “zero money-out-of-pocket” free, but it's also “free speech” free. That is, GIMP is developed by an international team of volunteer programmers who have agreed to keep the program's source code freely available for anyone to see, modify, and extend. Not only does this produce solid, powerful software, but it also provides a level of customization that makes GIMP very appealing to independent artists, small graphics companies, and computer graphics researchers, to name a few. With GIMP, you have the advantages of your own in-house graphics program without having to hire a team of programmers to lay the groundwork for you. This means that if GIMP doesn't have a feature and you need it, you have the option to add that feature yourself (or hire only one programmer to do it). That's from an artist's point of view. From a developer's perspective, having GIMP as a base starting point allows you to focus on creating the unique features that you need.

What Are GNU and Free Software?

If you're coming from the world of Windows or Macintosh, then the concept of Free Software may not be something you're too familiar with. Simply put, Free Software is software that you can use, modify, and share with virtually no restrictions. Although it's often distributed free of charge — occasionally referred to as “free as in beer” — Free Software is not to be confused with “freeware.” This is because of the all-important freedom to modify Free Software programs to do whatever you like. This is commonly referred to as being “free as in speech” and it's the primary thing that sets Free Software apart from software that's merely given away for free. For a program to be considered Free Software, users must be allowed unrestricted access to that program's source code. It is for this very reason that programs like GIMP can exist.

At this point, you may find yourself wondering why any software developer would ever give away their work for free. The answer to that question is surprisingly simple, but it varies from person to person. For some people, it's the idea that your computer (and everything on it) belongs to you and you should be allowed to use your computer as you see fit, without restriction. For others, it's a philosophy that stems from the belief that software is information and information should be freely available to everyone. And still other people approach it more pragmatically, noting that freely accessible source code is under the scrutiny of more eyes, ultimately leading to more stable software with fewer bugs and a lower probability of doing malicious things to your computer. Oftentimes, a Free Software developer's ideals involve a combination of these perspectives. The one commonality, though, is that they do this because they enjoy it. It's fun!

At the core of most Free Software projects — GIMP included — is a software license called the GNU General Public License, or GPL. This license is a clever use of copyright law that says you're free to modify a program and redistribute it, so long as you also make the source code to your changes freely available. Because this is basically using copyright law against itself, the GPL is often referred to as a copyleft license. The GPL was originally written by the founder of the Free Software Foundation, Richard Stallman, for the GNU Project. GNU is an acronym that stands for “GNU's Not Unix” and it was Stallman's project, which he started in 1983, to create a Free Software operating system. By 1992, the GNU Project had all of the necessary elements for this operating system with the exception of one thing: a central core to interface with hardware and manage processes, known as a kernel. Serendipitously, it's right around this time that a Free Software kernel developed by a Finnish programmer by the name of Linus Torvalds began reaching a usable level of maturity. This kernel, Linux, filled in that last gap and gave the GNU Project (and the world), a working Free Software operating system. Because of this, the operating system's proper name is GNU/Linux. However, for the sake of simplicity and common discourse, this book will simply refer to it as Linux. The GNU is implied.

Of course, it's not all roses and cake. GIMP is often suggested as a replacement for Adobe Photoshop and, as a result, has received a fair amount of criticism based on the comparison; some of it well-deserved. Probably one of the most controversial subjects is GIMP's interface, shown in Figure 1.1. It's been called everything: unconventional, obtuse, brilliant, and some things I can't repeat in this book. GIMP gets a bit of an unfair shake due to the proliferation of Photoshop; its interface isn't so much bad—it's just different. That's not to say that it's perfect, though. There are certainly some interface quirks you need to deal with. Part of the purpose of this book, however, is to help you work with GIMP's interface rather than against it. Hopefully with this book as your reference, you'll find that you will be limited only by your imagination when working with GIMP.

Figure 1.1 What you're greeted with by default when you open GIMP

The remainder of this chapter lets you hit the ground running, introducing you to GIMP's interface and letting you play with it. Before doing that, though, you need to have GIMP installed on your computer. Fortunately, GIMP is completely free and available for you to download off the Internet. Regardless of whether you're running Linux, Mac OS X, or Windows, the place to find the latest and greatest version of GIMP is on its web site at www.gimp.org. Each operating system has its own set of installation instructions for GIMP. As a matter of fact, www.gimp.org actually links to other sites for downloading and installing on Mac OS X and Windows. Because of this, you may want to take a look at Appendix A in this book for clear instructions on installing GIMP for your specific operating system.

Knowing What GIMP Can and Cannot Do

So what exactly can this little program do? GIMP is an extremely capable piece of software that can do quite a few things other image editing programs can't do, but it's helpful to have a clear understanding of where its current limitations lie. This book focuses on the features planned for or available in GIMP's 2.8 series, and for general-purpose graphics work GIMP performs admirably. However, print professionals may miss some useful features that they would expect from a raster graphics program like Photoshop.

For example, GIMP supports RGBA (Red, Green, Blue, Alpha) images with 8 bits per channel, grayscale images, and images with a fixed color palette. However, it does not currently have native support for the more print-friendly Pantone or CMYK (Cyan, Magenta, Yellow, Black) color spaces or images with 16 or 32 bits per channel. This makes it less capable for use in print and film because the CMYK color space can't produce all of the colors available in RGB, and film image editing requires the refined detail of high bit-depth color.

That's not to say there aren't ways around this. GIMP can still do CMYK color separations and, with a plug-in, export images in CMYK. It can also read the raw image data from many digital cameras, although it can't save back to those formats. You may also be surprised to know that GIMP does support embedded color profiles and allows accurate on-screen print simulation using integrated color management tools.

GIMP also has an advanced layer system that allows for all sorts of complex compositing tricks and it supports an impressively extensive list of image formats, including Photoshop's native PSD format. That's not to say that the support is seamless. Because GIMP doesn't have adjustment layers like Photoshop, reading PSD files that utilize adjustment layers lets you see the data in that layer, but none of the adjustment layer tricks that were used.

Most of these limitations are technical and it's largely just a matter of time before GIMP overcomes them, thanks to the very active developer and user community around GIMP. And contrary to a fairly vocal minority, these limitations don't prevent GIMP from being usable for professional work. A few limitations, however, like support for the Pantone color matching system, are based on proprietary information and algorithms. This means that because of GIMP's developers' dedication to keeping its source code freely available, that feature cannot be legally implemented and distributed with GIMP. However, the flip side to this is that the ability to extend GIMP is not limited to a small group of privileged programmers. Anyone can add to, improve, and even change GIMP to suit their specific needs. It cannot be overstated how valuable this extensibility is. It's one of the beautiful things about Free Software. It's that potential for anyone's specifically added feature to benefit everyone who uses the program. Like other creative software in the Free Software world, GIMP has benefited greatly from the contributions of artists who had never written code before in their life, but because of its openness, they were able to add a new feature that they needed.

However, perhaps the best way to understand what GIMP is capable of is to see the results for yourself. GIMP was used to capture all of the figures in this book. Along with downloading and using the program yourself, this is probably the best way to get an idea of what GIMP can do.

Working with GIMP's Interface

So let's get started with this and get your hands dirty. When you start GIMP for the first time, one of the first things that you might notice is the number of windows that it opens. This is especially noticeable to Windows users who are used to programs occupying a single space on their taskbar. This multi-windowed environment comes from GIMP's origin in Linux and Unix, with their unique and varied means of window management. Fortunately for the users who find this to be troublesome, this situation has been somewhat rectified as of GIMP 2.6.1 for Windows and Linux users and will continue to improve in future versions of GIMP. I cover this improved window behavior in more detail later in this chapter in the “Setting Preferences” section. The purpose of this chapter is to get you familiar with the main parts of GIMP so you can get up and running and then right to work quickly. Refer to Figure 1.1 to see the default layout of GIMP when you load it for the first time.

Windows and Menus

When you launch GIMP, you're greeted with a splash window that displays while GIMP preloads plug-ins and extensions into memory. This should only take a few seconds. Once GIMP loads, you typically have three visible windows on-screen: the Main Toolbox, shown in Figure 1.1, on the left, an image window at the center, and a dock on the right that includes dialogs for layers, brushes, and palettes. Each of these windows serves a specific important purpose in GIMP, but as you may have guessed, the main image window with the menu along the top is where all of the action starts. Practically all editing operations can happen directly from image windows and their menu options. When you do not have images loaded, all you have is a gray box with a silhouette of Wilbur, the GIMP mascot, and the menu bar at the top. However, when you load your first image in GIMP, it's placed in this window. If you have more than one image open, each one gets its own image window with its own accompanying menu options.

You will find the same menu options are available by right-clicking anywhere within the image area of any image window. When you right-click your mouse, you invoke a menu like the one shown in Figure 1.2. For users of other programs that do not supply this option, this may seem a bit strange, but I personally love it because I don't have to move my mouse as far to get to the menu item I'm looking for.

Figure 1.2 The menu that pops up when you right-click in the image window

Another thing that's a little bit different in GIMP from other software is that most of its windows and dialogs are functionally non-blocking. This means that just because you have the File Open, File Save, or Preferences windows up, GIMP does not prevent you from changing tools in the Toolbox or even doing edits on your image. This is incredibly useful in terms of productivity. You can be doing a time-consuming operation on one image and GIMP won't prevent you from working on another image while that happens. You can customize your preferences on the fly and change them while you're working to suit your needs as you roll along. Basically, GIMP sticks to doing what you tell it to do and does everything in its power to get out of your way while you're working.

The menu options available to you in the image window give you access to nearly every available action in GIMP. Here's a quick heads-up on what you can expect to find in each menu item:

File—This is where most of GIMP's file operations live. From here you can open, close, create, save, and export images. This menu also gives you the ability to acquire images like screenshots and images from a scanner. You can find more on the items accessible via the File menu in Chapter 3.Edit—The Edit menu is where a lot of the basic work gets done on your images. From here you can copy, paste, undo, and do basic actions like filling and stroking.Select—From this menu, you can control your selections within the image window. Not only do you have control over what's selected, but you can also control what GIMP does with that selection.View—This menu has a big influence on how you interact with the image window. Not only can you control zoom from here, but you can also show and hide features like guides and layer boundaries as well as turn on snapping.Image—This is where a good portion of the “heavy lifting” happens when you're working on an image. Chapter 2 has a lot more detail on the options here, but this menu allows you to perform basic transforms, size adjustments, cropping, and even a little bit of minor layer management.Layer—Of course, the really extensive layer management tools are in this menu. Nearly all of the functionality of the Layers dialog can be accessed from here, although it may be a bit more difficult. Chapter 6 is all about layers and covers this menu extensively.Colors—If there's anything color-related that you need to do, chances are good that it's going to happen by way of this menu. A whole bevy of color operations live here and each one is helpful for enhancing your images. You can find out more about this menu and adjusting colors in GIMP in Chapter 9.Tools—This menu is basically the functionality of your Toolbox all in one menu.Filters—Probably one of the largest, most extensive menus in all of GIMP, the Filters menu has an almost excessive number of potential ways to perform semi-automated effects on your images. This menu is so extensive and has so many options that all of Part IV is devoted to its contents.Video—The Video menu isn't available in most default installations of GIMP. It's included as part of the GIMP Animation Package, or GAP, and has some incredibly useful functions for modifying video and animation frames from within GIMP. Chapters 19 and 20 cover this functionality in depth.Windows—GIMP offers the potential to have quite a few open windows on your screen simultaneously. It's in your best interest to be able to manage those windows effectively. This menu is your tool to do just that.Help—No matter how long you've used a program as full-featured and complex as GIMP, there's a good chance that you'll need help with something somewhere along the line. This menu is your route to finding the help you need.

Another important thing to note is that you're not limited to just the three default windows that appear when you first load GIMP. Nearly every part of GIMP's interface can be detached and turned into its own window, including the main menu! Take a look back at the right-click menu in Figure 1.2 and notice the dashed lines at the top of it. If you left-click this dashed line, it will create another floating window just for this menu. To remove this window, simply click the dashed line again. Furthermore, notice that each of the submenus also features this dashed line. They can also be detached and turned into their own windows. You might find yourself asking why you'd ever want to do something like that, but imagine that you're performing the same operation over and over again. Simply clicking the same option more than once in a persistent menu is a lot faster than having to navigate from the base of the main menu every single time.

Warning

It's important to note that if you close the last remaining image window, GIMP quits and you will have to relaunch it. This isn't the case with the Toolbox or dock window. You can freely close either of these. The Toolbox can be returned by going to Windows ⇒ Toolbox (Ctrl+B) and the dock window can be brought back at Windows ⇒ Recently Closed Docks ⇒ Layers, Channels, Paths, etc.

Docks and Dialogs

Of course, menus aren't the only thing that can be detached. Each of GIMP's other two main windows are composed of a set of dockable dialogs that work as panels and can be detached, shuffled, and re-attached at will. This is most valuable in the dock window on the right-hand side with the layers, palettes, and brushes dialogs. By default, this window has two docks, separated by docking bars, as shown in Figure 1.3. The top dock holds dialogs for Layers, Channels, Paths, and GIMP's Undo History. The lower dock holds Brushes, Patterns, Gradients, and the Color Palette dialog. In each dock, the individual dialogs are accessible by the tabs at the top of the dock or by picking the dialog from Windows ⇒ Dockable Dialogs. If the icon in the tab isn't enough to remind you what the dialog is, you can hover your mouse over the tab for a few seconds and wait for the tooltip that describes the dialog to pop up.

Figure 1.3 The right-side utility window with the two default docks

You can resize the docks by left-clicking and dragging the docking bar that separates them. This is useful with more complex GIMP files that have a fairly high number of layers because it allows you to see as many of them as possible at the same time. You may notice that the docking bars at the top and bottom of the dock window are not draggable. However, if you hover your mouse over any of these docking bars for a couple seconds, a tooltip appears saying “You can drop dockable dialogs here.” To see how this works, left-click the tab for the Layers dialog and drag it up to the top docking bar. When your mouse pointer hovers over the docking bar, it should become highlighted. Release the left mouse button and you'll see that you've created a new dock at the top of this window. Notice that because this new dock has only the Layers dialog, there are no tabs at the top, just the word “Layers.” You can move the Layers dialog back to its original position by left-clicking that word, Layers, and dragging it to the dock below. You should notice that as you drag your mouse around the dock, certain parts get an outline or highlight. This is so you can tell exactly where you're placing the dialog. You can even use this to customize the order of the tabs in a particular dock. Just left-click the tab in question and drag it forward or back in the arrangement of tabs.

You can also completely detach any dockable dialog and let it float independently in its own window. As an example of how to do this, left-click the Layers tab at the top dock and drag it off the window. When you release your mouse button, a new window is created with the Layers dialog in it. From here, you can re-dock the Layers dialog the same way you would if you'd put it in its own dock. Alternatively, because you've created a new window with its own new dock, you could also take some of the other dialogs and dock them here. This is a great way to customize your GIMP layout to match your specific work style.

Clicking and dragging aren't the only ways to customize your GIMP layout. Many of these functions can be controlled from a Tab menu at the top of each dockable dialog. In Figure 1.3, notice a left-pointing triangle in a box at the top right of each dock. This is the Tab menu. Clicking it gives you a menu similar to the one you see in Figure 1.4.

Figure 1.4 Options available in the Tab menu

This menu allows you to do most of what you can do by mouse-clicking and dragging, as well as offers some specific controls for the dialog that you're currently working in. Following is a brief explanation of what each option does.

Dialog-specific context menu—Not all Tab menus have this one. However, for some dialogs, like Layers, Channels, and Paths, the first item of the Tab menu is a submenu to address specific features available to that dialog.Add Tab—This menu item brings up a submenu from which you can choose another dialog to add to the dock you're working in.Close Tab—Clicking this item removes the current dialog from the dock.Detach Tab—This item performs the same function as left-clicking and dragging the dialog off to create a new window and dock.Lock Tab to Dock—Enabling this option prevents you from detaching the current dialog from the dock. This is a good way to keep you from accidentally removing or moving a dialog.Preview Size—Like the dialog-specific menu, this option is only available on some dialogs, like Layers and Channels, which utilize small versions of the image you're working on. The options in this submenu allow you to control the size of those small images.Tab Style—By default, GIMP uses icons for all of the tabs. However, some people like having a little bit more clarity. The options available in this submenu allow you to customize how the dialog appears in the tab. You can have it show an icon, text, or both. Some dialogs, like Brushes and Patterns, also offer specialized options for Status, which shows an icon of the currently selected brush or pattern in the dialog.View as List/Grid—These options are only available on some dialogs and are mutually exclusive; you can use only one or the other. The best way to see it in action is to look at the Brushes dialog. By default, this is set to View as Grid. However, from the Tab menu, you can change it to View as List to get a little bit more information about each brush.Show Button Bar—By default, at the bottom of each dialog in the dock is a button bar with a set of quickly accessible buttons for doing common tasks with that dialog, such as saving presets or adding a new layer, channel, or brush. This menu item shows or hides the button bar for the dialog you're currently working in.Show Image Selection—At the very top of Figure 1.3 is a wide drop-down button with an image preview in it. This is the Image Selection drop-down and it allows you to pick the image that you want the dialog to give you information about. It's not available for all dialogs, but for the ones that use it, this menu item toggles its visibility.Auto Follow Active Image—By default, the Image Selection drop-down will automatically switch based on whichever image window is active, or in focus. However, there may be an occasion when you want to, for example, see the layers of one image while you're working on another. Toggling this option off will allow you to do just that. You can also do the same thing by clicking the Auto button next to the Image Selection drop-down.Move to Screen—If you're using GIMP in Windows, you may not see this option. This menu item takes advantage of a multi-display feature of the X Windowing System used on Linux and Unix machines. It allows you to do cool things like run GIMP on one computer and control it from another. In a case like that, each computer is considered a screen. This submenu allows you to send a GIMP dockable dialog to another screen. As of this writing, this feature is currently experimental and may crash GIMP. There's a chance it may not be in GIMP 2.8.

If you look in the Add Tab item of the Tab menu, you can get a good idea of the different dockable dialogs available to you. You can see this same menu if you go to an image window and click Windows ⇒ Dockable Dialogs. Each of these dialogs has a specific use and purpose that can really help your productivity when used effectively. The following list is a quick run-down of each dialog and what it can be used for.

Tool Options—For whichever tool you have selected, this dialog will show available options for it. By default, this dialog is the dock beneath the tools in the Toolbox window.Device Status—This dialog is most useful for users with a drawing tablet. It not only shows if you're currently using the mouse, stylus, or eraser, but also which tools are assigned to each of these. If you have a drawing tablet, check out Appendix B to see how to configure GIMP to recognize it.Layers—From this dialog, you can see the layers in the file you're working on as well as add, rearrange, merge, and remove layers. Because this dialog is so frequently used, there's a default keyboard shortcut for it: Ctrl+L. Chapter 6 covers layers in detail.Channels—This dialog serves dual purposes. Its primary use is to allow you to select and visualize the individual color channels in your image. However, if you are using selection masks, this dialog is also where those masks call home. You can find more on channels and this dialog in Chapter 7.Paths—Paths are curves that you can create in GIMP and use to create selections, masks, and even draw with. This dialog allows you to manage the paths you create. You can find out more about paths in GIMP by looking at Chapter 5.Colormap—If you're working with an image that has an indexed color palette, such as a GIF, where the image consists of a small number of discrete colors rather than the full RGB color range, you can use this dialog to see these colors and modify them.Histogram—When working with images, a histogram is a chart that shows the distribution of the values in that image. This is a good statistical way to check the color balance of your image. Note that you cannot edit the histogram from here. To do that, you'll need to use the Levels tool from the Color menu. For more on this, see Chapter 9.Selection Editor—This is a cool little dialog that comes in handy when you're making selections in GIMP. Not only does it display any current selection, but it also offers a quick way to outline that selection or save it to a channel or a path.Navigation—The Navigation dialog offers a quick and painless way to zoom in and see specific parts of your image. It's particularly helpful on very high-resolution images.Undo History—This dialog shows a list of each of the actions you perform on an image in chronological order and allows you to undo and redo them. Two things to note here, though. First, when you close a file, its undo history is not saved with it; you lose that data. Also, you cannot arbitrarily undo just one action in a series of actions. If you undo something, you basically go back to the last action you did before it.Pointer—The Pointer dialog is a lot more useful than you might think. It gives you immediate and exact feedback about where your mouse is in your image. This is useful not only for picking colors, but also for determining where something is, down to the pixel.Sample Points—This dialog is similar to the Pointer dialog, but it allows you to pick four specific points in an image you're working on and gives you feedback about them in real time as you work. This is helpful if you know a specific part of your image is supposed to maintain certain color values and you want to monitor that.Colors—These are the colors GIMP can use. From this dialog, you can set your foreground and background colors from a variety of color selectors, including the GIMP default, watercolor, wheel/triangle, CMYK, color swatches, or a set of sliders.Brushes—This dialog is extremely useful when you are painting in GIMP. It allows you to select, edit, and manage your GIMP brushes. Because it's used frequently, its default keyboard shortcut is Shift+Ctrl+B. You can find more information on brushes in Chapter 11.Patterns—When doing color fills and other automated tasks, patterns can be quite helpful. This dialog helps you manage your patterns from within GIMP. You can access it quickly by using the keyboard shortcut Shift+Ctrl+P. You can find out more about creating patterns in Chapter 11.Gradients—Gradients are very helpful tools when you are creating images in GIMP and this dialog, which you can quickly access with the Ctrl+G shortcut, is where you manage and modify preset gradients. Chapter 11 shows some tricks on how to get the most out of gradients.Palettes—Like with the Colormap dialog, this one is specifically useful for images with an indexed color palette. From here, you can choose from a set of preset palettes or create your own.Fonts—This dialog is specifically meant for the Text tool (see Chapter 10), but it's a good, quick way to see what fonts you have available from within GIMP. Also, if you've added a new font to your system while working, this dialog will allow you to update the list of available fonts without having to restart GIMP.Buffers—Buffers are pretty useful little things in GIMP. You can take a selection and save it as a buffer by navigating to Edit ⇒ Buffer ⇒ Copy Named. This adds the buffer to the list in this dialog. From there, you can create a new image with the buffer or paste it back into the image whenever you like. Note, however, that like the Undo History, buffers do not get saved with a file. So if you close GIMP, those buffers are gone forever.Images—