One of the best graphics clients available is The GIMP. The GIMP is a free, GPLed image editor with sophisticated capabilities that can import and export more than 30 different graphics formats, including files created with Adobe Photoshop. It is often compared with Photoshop, and The GIMP represents one of the GNU Project’s first significant successes. Many images in Linux were prepared with The GIMP.

The GIMP can be found under the Applications, Graphics menu or can be started by using the command line, like this:

$ gimp &

You see an installation dialog box when The GIMP is started for the first time, and then a series of dialog boxes that display information regarding the creation and contents of a local GIMP directory. This directory can contain personal settings, preferences, external application resource files, temporary files, and symbolic links to external software tools used by the editor.

After the initial configuration has finished, The GIMP’s main windows and toolboxes appear. The GIMP’s main window contains tools used for selecting, drawing, moving, view enlarging or reducing, airbrushing, painting, smudging, copying, filling, and selecting color. Depending on the version installed on your system, the toolbox can host more than 25 different tools.

The toolbox’s File, Xtns, and Help menus are used for file operations (including the capability to send the current image by electronic mail), image acquisition or manipulation, and documentation, respectively. If you right-click an open image window, you see the wealth of The GIMP’s menus, as shown in Figure 11.1.

Figure 11.1. Right-click on an image window to access The GIMP’s cascading menus.

Webcams are typically small, low-resolution cameras connected to your computer via a parallel port or USB port. The camera can act in two modes: streaming (for a series of images of a moving object) and grabbing (for a single still image). The most common uses for webcams include videoconferencing and web voyeurism. The latter is not as lurid as it might sound, although some webcam sites are notorious for their pornographic content. Webcams can be used to send almost-live images to an online correspondent; many people include screen grabs of themselves at their computer workstations just because they can.

You can use any of the video applications that can access a video4linux device to view webcam or still camera images in Fedora. You also can use GnomeMeeting (discussed in Chapter 8, “On the Internet: Surfing the Web, Writing Email, and Reading the News”) as a viewer for your webcam.

Not all webcams are supported in Linux and the drivers are based on the chipset used, rather than the model or manufacturer. Some of the files in /usr/src/linux-2.6/Documentation/usb contain information about USB webcams and drivers supported by Fedora, including

Documentation on parallel port cameras, including the CQ cam (Cqcam.txt) and CPiA camera (README.cpia), is found in /usr/src/linux-2.6/Documentation/video4linux/ if you have installed the kernel documentation on your computer.

Digital cameras are one of the major success stories of the last few years. Now you can take pictures and see previews of your pictures immediately. The pictures themselves are stored on discs or memory cards that can be easily plugged into Fedora for further manipulation using The GIMP or other software. Unfortunately, most of the supplied software that comes with the cameras tend to be for Windows users only, making you reliant on the packages supplied with Fedora.

Thankfully, due to the good development carried out in Fedora and GNOME, you are now able to plug pretty much any camera into your computer using a USB interface and Fedora automatically recognizes the camera as a USB mass storage device. You can even set Fedora to recognize when a camera is plugged in so that it automatically imports your photographs for you.

To do this, you need to set up your settings for removable drives and media. You can find this in the System, Preferences menu. Click the Cameras tab and select the option to import digital photographs when connected (see Figure 11.2).

Figure 11.2. Use GNOME’s intelligent handling of removable media by setting it to import your photographs automatically.

Now whenever you connect a digital camera to your computer GNOME automatically detects it (see Figure 11.3), and asks whether you want to import the photographs.

Figure 11.3. GNOME detects the presence of a digital camera and asks whether the photos should be imported.

By default GNOME uses the excellent gThumb package (see Figure 11.4), which, although basic-looking, offers an easy-to-use interface and powerful cataloging capabilities.

Figure 11.4. Make use of gThumb to manage your extensive photo collection.

With the inclusion of Mono into Fedora Extras, Fedora now has access to the superb F-Spot photo management application. However, F-Spot is not installed by default, so you have to do a quick install by using the command

# yum install f-spot

which retrieves the F-Spot program and the other required components.

When F-Spot is installed, you can find it under the Applications, Graphics menu listed as F-Spot Photo Manager. If you have used the popular Google Picasa application, you will feel instantly at home with F-Spot because it is similar in many ways.

The first time you open F-Spot, you are asked to import your first batch of photographs as shown in Figure 11.5. You can also assign a tag to them, if you want to track particular types of photographs. You might want to allow F-Spot to copy the photograph to a new directory, Photos—something that helps you organize your photos on the system.

Figure 11.5. The versatile F-Spot makes adding photos to your library easy.

When you are ready, click Import to let F-Spot import the photos into the library. The pictures appear in the F-Spot library, and are stored according to the date they were taken. This information is given to F-Spot by the EXIF information that your camera stores each time you take a picture. In Figure 11.6, you can see the standard F-Spot window.

Figure 11.6. Browse through your extensive photo collection and correct minor problems using F-Spot.

You browse through your photographs using the timeline across the top of the window and you can do some minor editing by double-clicking on any photograph. F-Spot is still in its infancy, but development is ongoing, so keep a eye open for any major updates.

Image file formats are developed to serve a specific technical purpose (lossless compression, for example, where the file size is reduced without sacrificing image quality) or to meet a need for a proprietary format for competitive reasons. Many file formats are covered by one or more patents. For example, the GIF format has fallen into disfavor with the open-source crowd because the patent holder has only recently decided to begin enforcing his patent rights.

If you want to view or manipulate an image, you need to identify the file format to choose the right tool for working with the image. The file’s extension is your first indicator of the file’s format. The graphics image formats supported by the applications included with Red Hat include

An extensive list of image file extensions can be found in the man page for ImageMagick, an excellent application included with Fedora, which you learn more about in upcoming sections of this chapter.

Often, a file you want to manipulate in some way is in a format that cannot be used by either your graphics application or the final application. The solution is to convert the image file—sometimes through several formats. The convert utility from ImageMagick is useful as is the netpbm family of utilities. If it is not already installed, ImageMagick can be installed with the Add Remove Software GUI found in the System Settings menu; the netpbm tools are always installed by default.

The convert utility converts between image formats recognized by ImageMagick. Color depth and size also can be manipulated during the conversion process. You can use ImageMagick to append images, surround them with borders, labels, rotate and shade them, and perform other manipulations well-suited to scripting. Commands associated with ImageMagick include display, animate, identify, and import. The application supports more than 130 different image formats—all listed in the man page for ImageMagick.

The netpbm tools are installed by default because they compose the underpinnings of graphics format manipulation. The man page for each image format lists related conversion utilities; the number of those utilities gives you some indication of the way that format is used and shows how one is built on another:

You can use graphics manipulation tools to capture images that are displayed on your computer screen. Although this technique was used for the production of this book, it has broader uses; there is truth to the cliché that a picture is worth a thousand words. Sometimes it is easier to show an example than it is to describe it.

A captured screen image (also called a screen grab or a screenshot) can be used to illustrate an error in the display of an application (a font problem, for example) or an error dialog that is too complex to copy down by hand. You might just want to share an image of your beautifully crafted custom desktop configuration with your friends or illustrate your written documents. In this section, you learn how to capture screen images for these and other purposes.

When using the GNOME desktop, you can take advantage of the built-in screenshot mechanism (gnome-panel-screenshot). Access this tool by pressing the Print Screen key. (Alt+Print Screen takes a screenshot of only the window that has focus on a desktop.) Captured images are saved in .png format.

You also can capture screen images from a remote computer using tools supported by Fedora. The import command (one of ImageMagick’s commands) was used to take the screenshots for this book; for example, using a local computer and a remote computer on a LAN.

First, we ran $ xhost + on the remote computer to allow another computer access to the X server on the remote machine; the command to take the screenshot is run on our local machine like this:

$ import -window root -display 192.168.2.4:0 12fig07.jpg

This utility made a difficult task easy because the publisher required the screenshots be done from an 800×600 screen (too small to comfortably work in) to accommodate its printing and production equipment.

We could also have used the classic UNIX tool xwd to take screenshots. The command would have looked similar to that of import:

$ xwd -root -display 192.168.2.4:0 -out 12fig07.jpg

Although the screenshots could have been taken with The GIMP and saved in the appropriate format, we would have had to run The GIMP on that computer and navigate the menus every time we captured an image—the remote option of import was very convenient.

We did not use Ksnapshot (not included in the menus, but available from the command line) because it does not support the .pcx format the publisher used to use and it must be run locally. However, it can take screenshots easily and is our preferred tool for use on a single machine.