11.2. Manipulating Images with the GIMP
The GNU Image Manipulation Program (GIMP) is a powerful tool that can be used to create, alter, manipulate, and enhance digital image files — photographs, scanned images, computer-generated images, and more. This section offers a quick overview of the GIMP and refers you to comprehensive references for learning more about it.
11.2.1. GIMP Basics
To use the GIMP, you will need to know some of the basics. From a shell prompt, you start the GIMP using the command gimp, or you can start the GIMP from the desktop by choosing Main Menu => Graphics => The GIMP.
Figure 11-5 shows a typical GIMP session in action.
11.2.2. Loading a File
To load an existing file, select File => Open. You will see the Load Image dialog, as shown in Figure 11-6.
The Load Image dialog displays your working directory — the directory you were in when the GIMP was launched. You can navigate up and down the file system tree by double-clicking on the Directories list on the left, then selecting a file to open from the Files list on the right.
File name completion is supported by the
GIMP. If you type the first letter (or
more) of a file name into the Selection field and
press the
The file you select appears in the Selection field near the bottom of the dialog. A thumbnail preview is displayed in the dialog; alternatively, a Generate Preview button is displayed. If you want to see a thumbnail of the image, click on the Generate Preview button.
Once you have selected a file, click on the OK button to open it. You can also double-click on a file name to open it.
11.2.3. Saving a File
To save an image file, right click on the image and choose File => Save (or Save as). You will see the Save Image dialog if you choose Save as or if you choose Save and the file has not been saved before.
The Save Image dialog looks almost exactly like the Load Image dialog and navigation of the file system tree and choosing files works in the same way.
When you are saving an image, you must choose an image format. The GIMP supports a wide variety of image formats, including .gif, .png, .jpg, and .bmp.
11.2.4. GIMP Options
Like many applications, the GIMP provides more than one method to accomplish tasks. The easiest way to work with images is to right-click the image, which displays a set of menus containing most of the GIMP's many capabilities, including image sizing, rotation, and filter application.
For example, imagine you have a picture that you would like to modify to make it look as if it were clipped from a newspaper. To do this, right-click on the image and select Filters => Distorts => Newsprint.... Select the quantity of lines per inch using the sliders. When you reach a desired quantity and are ready to render the image, click OK. The GIMP then renders the image with the new effect applied. Figure 11-7 shows an example of an image after the Newsprint filter has been applied:
The Toolbox also has several easily accessible functions. Using the Toolbox, you can add text to images, erase regions of an image, or even fill selected regions with the color of your choice.
For example, if you wish to add text to a file, select the
button and click on your image. This loads the
Text Tool dialog box, where you can choose a font
and type some text in the provided text box. Click
OK and your text is displayed as a floating
section on the image. You can then move the text to the position you
wish using the Move Layers tool. Figure 11-8 shows our photo with exciting new
text:
As you can see, the GIMP is a powerful image editing tool, and it takes some time to master all of its functions. Try exploring some of the options yourself. If you make a mistake, do not worry. You can always undo your mistakes by right-clicking on the image and choosing Edit => Undo.