1. What Is GIMP?

This chapter gives you a basic introduction to the GIMP graphics editor, including the ins and outs of the interface and how to find the many of the commonly used tools.

GIMP is an open source graphics editor with capabilities similar to those of Adobe Photoshop. The name GIMP stands for GNU Image Manipulation Program, which describes the license by which GIMP is released. GIMP can be downloaded and used by anyone; versions exist for numerous operating systems, including Windows, Linux, and Mac OS.

GIMP has nearly everything you’ll ever need from a graphics editing program. It can be used for simple tasks, such as image cropping and rotating, and for photo editing and the creation of complex graphic art used in web design. This includes such image types as avatars, signatures, and wallpapers. It can also convert image formats and do online batch processing.

Although the capabilities of GIMP are vast, this book is written to get a beginning GIMP user up and running fast and focuses on performing more of the common tasks you’ll want out of an image manipulation application. You will also discover that GIMP saves images by default its own file format type: xcf.

Getting Started with GIMP

In the Introduction, you learned how to find, download, and install GIMP on your computer. GIMP is equally at home on Windows, MAC OS, and Linux, but because most desktop users are on Windows XP or Vista, the examples used here show GIMP from the Windows point of view.

Exploring GIMP

The first step in using GIMP is to launch the application on your computer. When GIMP was installed, a shortcut should have automatically been installed on your desktop, so the easiest way to launch GIMP is to double-click the GIMP icon. In Windows XP, you can also click Start, All Programs, and then click GIMP.

When you launch GIMP for the first time, you’ll notice that performance is somewhat slow. A variety of tasks have to be performed upon first launch, including creating the .gimp-2.6 subdirectory. In Windows, this is located at C:Documents and Settingsusername, where username is the name of the computer user who installed GIMP. After the first time you close GIMP, you’ll notice it opens a lot faster. You can see the basic GIMP user interface in Figure 1.1.

Figure 1.1. The GIMP interface contains a toolbox, an Image window, and a Layers, Channels, and Paths box.

Exploring the Toolbox and Options Box

When GIMP launches, you’ll see what seems to be three different dialog boxes. The first is the Toolbox, containing the different tool options available in GIMP. The next is the Image window, which contains all the menus and commands you’ll use when you need to manipulate in open image. The last dialog is the Layers, Channels, Paths, and Brushes dialog, which offers the most commonly used GIMP utilities. Right now, we’ll focus on the first two dialogs and then cover the tools presented in the third dialog in later parts of the book.

The Toolbox is composed of two boxes: the Main Toolbox, which contains all the buttons you’ll use to choose GIMP tools, and the Tools Options box, which shows you the options available for any selected tool. In the current example, the Paintbrush is selected in the Main Toolbox and the options for the Paintbrush are displayed in the Tools Options box just below (see Figure 1.2).

Figure 1.2. The GIMP Toolbox.

Clicking a different tool displays the options for that tool. If an image was open, the Tool Options box would be tabbed, so you could configure both the selected tool and whatever aspect you are working on in the open image, including layers and channels.

You can also open other dialog boxes to make it easier to work with additional tools, such as Brushes. You can open as many dialog boxes are you require from the Image window.

LET ME TRY IT

Opening Dialog Boxes

1. On the Image window, click Windows in the toolbar.
2. Scroll over Dockable Dialogs.
3. When the menu appears, click a dialog option such as Brushes.
4. Select the size of brush by clicking the brush.
5. When you’re done with the dialog, close it by clicking the X in the upper right of the box.

When you select a paintbrush in the Brushes dialog, the size and type will appear in the upper left of the dialog. The arrow near the upper right of the dialog will open a menu with additional options. The easiest way to learn GIMP is to start using it right away. You’ll start by creating and editing a simple image.

Trying Out GIMP

Open GIMP, either by double-clicking the desktop icon or clicking Start, All Programs, and then clicking GIMP.

On the Image Window, click File, New. When the Create a New Image dialog opens, accept the default settings and click OK to open a blank canvas. On the Image Window toolbar, click Image as shown in Figure 1.3.

Figure 1.3. Click Image in the Image Window toolbar to open the menu.

In the menu that appears, hover the cursor over Guides, and when the new menu opens, click New Guide.

When the New Guides dialog appears, accept the default Horizontal selection for direction and for Position, use the arrow to select 100, and click OK. Repeat those actions again, but this time, select 300 for the position of the guide. Next, change the direction from Horizontal to vertical, keep the position setting and click OK. Finally, keep the direction Vertical and set the position for 100 and click OK. You should now have four guides that create a rectangle on the canvas.

The numbers you have been selecting are measurements in pixels and describe where on the canvas to place each of the guides.

On the upper section of the Toolbox, select the Elliptical select tool by clicking on it. The tool looks like an oval and when you hover over it, pop-up text with the name of the tool appears. Move the cursor over the upper left corner of the box you created with the guides, click and hold the mouse button, and drag the cursor down to the lower right corner.

On the Image Window menu, click Edit, and then click Stroke Selection. On the Stroke Selection dialog under Stroke line, use the Line width arrows to select 3.0, accept the rest of the default values, and then click Stroke as shown in Figure 1.4.

Figure 1.4. The Stroke Selection Dialog.

Now click your cursor anywhere on the canvas to remove the selection. On the Image Window menu, click Image, hover over Guides, and then click Remove all Guides.

On the Main Toolbox, click the Foreground color editor to open it. In the Change Foreground Color dialog, in the HTML notation field, type FFFF00 and then click OK. This changes the foreground color from the default black to yellow as shown in Figure 1.5. The number you just typed is a hexadecimal value that commonly references the color yellow. You’ll learn other methods of choosing colors in Chapter 3, “Managing Colors.”

Figure 1.5. The Foreground Color Editor let’s you select colors to use in GIMP.

In the Toolbox, select the Bucket Fill tool. It looks like a paint can that is half tipped. Now click inside the circle you created and fill it with yellow. Once you’re done, open the Foreground color editor again and this time, choose black from the options available under the HTML notation field, and then click OK.

On the Toolbox, click the Paintbrush tool. On the Paintbrush tool tab, click the Brush button to open the brush selection dialog. Click each of the brushes until you locate Circle (07) as shown in Figure 1.6. You can choose any brush size and type that suits you, but I’m selecting this brush to produce a specific effect.

Figure 1.6. Select a brush size and type in Toolbox Options.

The field to the right of the Brush button changes each time you click a brush, telling you the type and size of the brush.

Imagining the circle as a cartoon face, click once where you think the left eye should go on the face. Click again where you want to put the right eye. Go back to the Toolbox and select the Paths tool. It looks like an old fashioned fountain pen point. On the circle, imagining it to be a face, click once where you want to put the left side of the mouth, and click again where you want to put the right side of the mouth. Put your cursor over the middle of the line you just created and drag it down to create a smile.

On the Image Window toolbar, click Edit and then click Stroke Path (not Stroke Selection). Change the line width to 3.0, accept the rest of the default settings, and then click Stroke. Select another tool such as the Move tool and then click the canvas to remove the path selections.

To save your new drawing, click File and then click Save As. Give the new drawing a name such as “smiley”. If necessary, navigate to the folder where you want to save your drawing and then click Save. Note that if you don’t specify an image format extension when you save the drawing, it will be saved using GIMP’s default .xcf extension.

Viewing Settings and Options

There are details you may not have noticed while you were creating “smiley” that you’ll review now to learn more about how GIMP works. This is why you left everything open after you saved your drawing.

It is very helpful to have separate tabs appear for each tool or other feature you select while you are working on an image. This is not a default behavior, so you will need to learn how to add tabs to the Tool Options box.

Configuring Toolbox Tabs

Each tab open in Toolbox Options has an arrow that, when clicked, lets you further configure the tab. The options available vary depending on the type of tab, but an example from the Paintbrush tab shows the following:

• Tool Options Menu—Offers menus that let you select features to modify the selected tool.

• Add Tab—Opens a menu that lets you add a variety of GIMP tools to the Toolbox Options box as tabs.

• Close Tab—Closes the current tab in Toolbox Options.

• Detach Tab—Lets you remove the tab from Toolbox Options but keeps it open and available.

• Lock Tab to Dock—Prevents the tab from being dragged with the mouse.

• Tab Style—Lets you change the appearance of the tab.

• Show Button Bar—Lets you add or remove the button bar at the bottom of Toolbox Options.

Viewing the Paintbrush Tool Options

First, notice that the Tools Options box now has two tabs. The first should be for the last tool you selected in the Main Toolbox, and the other represents the details for the drawing that is still open.

If the Paintbrush tool is still selected from the previous exercise, you’ll notice the following settings as shown in Figure 1.7.

Figure 1.7. Toolbox Options for the Paintbrush Tool.

• Mode—Clicking this drop-down menu gives you a variety of options in determining the interaction of the colors applied with the brush and the other colors in your file.

• Opacity—The slider controls how opaque the paintbrush line will appear: from 100, or completely opaque, to 0, or invisible.

• Brush—Click the Brush button to open the Brushes dialog.

• Scale—Use this slider to control the size of the brush. The default setting is 1.00.

• Brush Dynamics—Expand this option to control the mapping of various brush parameters, such as opacity or hardness, to one or more of the three input dynamics: Pressure, Velocity, or Random.

• Fade Out—Select this check box to cause the line from the brush to fade out over a specific distance of a stroke.

• Apply Jitter—Control the spacing in the brush stroke to make a continual line appear or to “jitter” the line as if the brush were shaking.

• Incremental—Deselect this check box if you want successive click strokes of the brush over the same line to add or increment color when you use a reduced opacity setting. Select this check box if you do not want to add or increment color when making successive click strokes when you use a reduced opacity setting.

• Use Color from Gradient—This feature lets you use a gradient color in the brush stroke.

Viewing Image Options

Now click the Imaged tab to see what options are currently available for your drawing as shown in Figure 1.8.

Figure 1.8. Viewing the Image tab.

The options should be as follows:

• The Image thumbnail.

• The Raise Image arrow.

• The Create New Display button, to create a duplicate of the image.

• The Delete button.

If you had added layers to the drawing or performed other work, those would show in the display of this tab.

Viewing and Configuring Tool Options in a Separate Dialog

Each tool you can select in the Main Toolbox has its own options that let you customize the tool and the tool’s tab. This book won’t present each and every tool to you at this level of detail, but you will have an understanding of what you are able to modify for tools and tabs and can apply that to any of the tools or tabs.

You can also open a separate Brushes dialog that has a number of additional configuration settings you can use. To find it, on the Image Window toolbar, click Windows, Dockable Dialogs, and then click Brushes. A free standing Brushes dialog appears that offers more options than the Brushes dialog you see when you click on Brush on the Paintbrush tool tab as shown in Figure 1.9.

• Brush Size and Shape—This is displayed for whatever brush is selected in the dialog.

• Spacing—This slider controls the size of the brush. The default is 20.0.

• Brush Editor—Opens a dialog that lets you edit the properties of custom brushes. The dialog opens as read-only for GIMP’s default brushes.

• New Brush—Lets you create a new, customized brush.

• Duplicate Brush—Creates a duplicate of the selected brush.

• Delete Brush—Deletes the selected brush.

• Refresh Brushes—Refreshes the view of the brushes in the dialog, used typically when a new brush has been added but is not yet visible.

Figure 1.9. Dockable Brushes Dialog.

GIMP comes with a variety of brushes, gradients and plug-ins, but you can locate thousands more and download them free from various websites and install them in GIMP on your computer. You can use these brushes to create any number of interesting artistic effects. Here’s an example of how this is done:

Reviewing the Image Window

Now that you’ve looked at the Toolbox Options, let’s take another look at the Image window. The toolbar contains various selections, each with menus that let you manage any drawing or image to a very fine degree. The first, and in my opinion, most important tool is Undo.

LET ME TRY IT

Using the Text and Undo Tools

Nobody’s perfect. Everyone makes mistakes and chances are, you’ll make a mistake in one or more of the images you create or edit with GIMP. Fortunately, GIMP can be very forgiving. Go back to smiley to see how it works.

1. On the Main Toolbox, select the Text tool.
2. Click in the middle of Smiley’s forehead to open the Text Editor.
3. Type a word, such as Smiley, into the Text Editor box and then click Close.
4. Save your drawing, but leave it open.
5. Click Edit in the Image window toolbar, and then click Undo Text Layer.
6. Repeat this step until the text is gone.

Even after the drawing is saved, you can still undo work that you’ve done as long as you haven’t closed the image. At this point, the drawing is unsaved, so if you want to make sure your previous mistake doesn’t come back, save it again.

Viewing Text Tool Options

Even though you’ve removed the text layer from your drawing, the Text tool is still selected. Look at the Toolbox Options review the Text Tool tab as shown in Figure 1.10.

• Font—Click this to open the Fonts menu and select the desired font.

• Size—Use the arrows to select the size value, and use the drop-down menu to the right to select the scale, such as pixels or inches.

• Hinting—Select this check box to change the font’s outline, creating a crisper bitmap at small sizes.

• Force Auto-hinter—Automatically uses Hinting for fonts.

• Antialiasing—Smooths rounded and angled shapes to reduce jagged-looking edges on fonts used at large sizes.

• Color—Lets you select a color for the font from the Color Editor.

• Justify—Lets you select justification options.

• Indentation—Control the indentation of the first line.

• Line Spacing—Control spacing between lines.

• Letter Spacing—Control spacing between letters.

• Text Along Path—When active, lets you add text along a selected path.

• Path from Text—When active, lets you turn text into a selected path.

Figure 1.10. Finding the Text Tool on the Toolbox.

After you’ve selected the Text tool and click in an image to add text, the GIMP Text Editor window opens. In the available field, you can type the desired text and watch it appear in the image. The Text Editor window also has some configuration buttons.

Click Open to open a file browser and load text from a file on your computer. Click Clear to clear any text you have typed in the editor. Clicking LTR causes text to be written left to right, which is the default behavior. Clicking RTL causes text to be written right to left. To make sure the font you selected on the Text tool tab is used, click the Use selected font check box.

Installing Additional Fonts

You learned previously that you can download and add brushes and gradients into GIMP. It’s also possible to add more fonts to GIMP. If you create a lot of graphics that require words or branding, such as title bars or banners for websites, you probably won’t always be satisfied with GIMP’s default font selections. Here’s more about installing fonts in GIMP:

Image Scaling with GIMP

A number of small but illuminating exercises can help you learn more about how to use GIMP. For instance, you may locate a drawing or other image that you want to use in a document or on a website, but it’s the wrong size. Resizing with GIMP is a snap.

Using the Image Scaling Feature

Not every image you work with will be of the correct size or resolution. You might want to turn a computer screen wallpaper into a small image for posting on a blog or other similar venue. Fortunately, GIMP makes this fairly simple.

For this exercise, you’ll need an already created photograph, drawing, or other image. It doesn’t have to be like the example you’re about to see, but it will help if the image is relatively large.

LET ME TRY IT

1. Navigate to a folder on your computer that contains images, such as My Pictures.
2. Double-click the image to open with GIMP.
   

   If the image doesn’t open in GIMP, right-click the image and select Edit with GIMP.

3. In the Image window toolbar menu bar along the top of the image, click Image and then click Scale Image.
4. When the Scale Image dialog opens, leave all the default settings unchanged and click in the Width field under Image Size.
5. Change the number in the Width field to be about half its current value, and then click Scale.
   

   The ratio between Width and Height is automatically preserved.

6. Once the image has been scale down to the desired size, save the image in its current format.

The image has been scaled to the size you specified in pixels (the default measurement). In the Image window toolbar, click Edit and then click Undo Scale Image to return the graphic to its original size, and then save it.

I’ll include that info on jpg when I redo the audio. I’m adding more information on scaling below.

Now that the image has been returned to its original size, click Image and then Scale Image again, and take a closer look at the Scale Image dialog as shown in Figure 1.11.

Figure 1.11. The Scale Image dialog.

• Width—Lets you set the width of the image being scaled.

• Height—Lets you set the height of the image being scaled.

• Image Size Link—This feature, unless disabled, maintains the width and height ratio of the image during scaling.

• Image Size Measurement—Lets you select the measurement type by which to measure the image, such as pixels or inches.

• X Resolution—Lets you set the resolution along the X-axis of the image.

• Y Resolution—Lets you set the resolution along the Y-axis of the image.

• Resolution Link—Maintains, unless disabled, the ratio between the X- and Y-axis during scaling.

• Resolution Measurement—Lets you select the measurement type by which to measure the imaging, such as pixels/in or pixels/mm.

• Interpolation—Lets you select the method used to increase or decrease the number of pixels in the image during scaling.

Although scaling an image to get it to a desired size is easy to do, it should not be performed lightly. You can’t just expect to change the size of an image and not affect the overall presentation. Basically, when you choose to scale a digital image, you are changing the size at the expense of image quality such as smoothness and sharpness. Whenever you increase the size of an image, the pixels making up the image become more apparent. This decreases the overall image quality and causes the graphic to appear softer, reducing detail. Reducing an image’s size will seem to increase apparent smoothness and sharpness.

Linear interpolation is fairly good at preserving smooth contours when increasing the size of an image but also results in addition softening of detail. Even though softened, you can still see some jaggedness in the image as the size is increased.

Cubic interpolation works better for scaling than Linear, preserving contours as the image size is increased. This is the default scaling method in GIMP because it produces fairly decent quality without taking a great deal of time.

Sinc (Lanczos3) interpolation is the best choice for maintaining smoothness and quality as you increase size, but takes the longest amount of time.

No method of increasing the size of an image by scaling is perfect and eventually, as you increase the size, details will be lost and imperfections will become more visible.

What you’ve seen so far is just the smallest fraction of what GIMP is capable of, but you now have an idea of how to find tools and settings in GIMP that help you accomplish image creation and editing tasks. The next chapter will get you into more in-depth editing of drawings and photos.