Lab 5: Image Editing with the GIMP

There are several image editing tools for Windows and Linux.
Today we will focus on the GIMP (GNU Image Manipulation Program).
The GIMP is a very powerful bitmap and vector graphics editor similar to Adobe Photoshop and PaintShop Pro.
ImageMagick is much easier to use but its features are more limited.

Starting

1. Click the K menu, move to Multimedia, move to Graphics, and click The Gimp.
2. If you are asked to configure The GIMP, just click OK or press Enter several times.
3. The tip of the day gives some helpful hints to get you started. Click Close after reading a few tips.

Windows

• The ToolBox window has several tools for selecting, moving and modifying images.
• Tool Options shows options for the currently selected tool.
• Brush Selection changes the size and shape of the brush for drawing lines and curves.
• Layers, Channels & Paths shows the different layers in your image and whether they are transparent.

Creating a New Image

1. Click File, New. Specify width 300, height 100, transparent. Click OK.
2. A window labeled Untitled appears. The checkered background indicates that it is transparent.
3. Right-click in that window, move to File, click Save As, and type lastname .xcf where lastname is your last name.

Adding Text

1. Double-click the Text tool (T in the Gimp window).
2. Tick the Use Dynamic Text box. Click Close.
3. Click in the image window. Select a font (e.g. indigo joker), style and size.
4. Type your name and preview it. The GNU Dynamic Text tool creates another layer.

Selecting Colours

• Click the Gimp, Watercolor, Triangle and GTK selectors. Use colour wheels, spectrums, sliders or hex values.
• Hue is the colour, saturation is the amount of a colour, and value is the brightness or darkness.
• You can also choose RGB colour values. For web-safe colours, you can type the hex triplet e.g. #ffcc99.

Adding a Brush Stroke

1. Click the brush tool. Select a brush shape. Select a different colour.
2. Click in the Background layer of the image in the Layers window.
3. Underline your name with a brush stroke by dragging the mouse.

Moving Graphics

1. Click the GDynText Layer in the Layers window.
2. Click the Move tool (four arrows).
3. Drag the text to reposition it to be on top of the brush stroke. Note that different layers are moved independently.
4. Click the Rotate tool.
5. Drag the text to rotate it slightly and click Rotate.

Saving and Exporting

• Save your changes by pressing Ctrl-S.
• Right-click the image and select File, Save As. Type lastname.gif and click Save.
• You will be asked to export the file by merging layers into one and indexing the colours. Click Export.
• If you want to change the image further, you should open the .xcf file, make changes, save and export again.

Photo Editing

1. Open mandrill.jpg or find another .jpg photograph.
   • e.g. type find / -name *.jpg -print at the shell prompt, or use the find feature in your file browser.
2. Open it in the GIMP by choosing Open from the File menu.
3. For the following steps, right-click the image and select the Image menu.
4. Choose Mode and click Grayscale. Click Undo. Choose Mode again and select Indexed.
   • Select Use Custom Palette, select Web to see the 216 colours, click Close and click OK. This makes a web-safe image.
5. Choose Colors. Try options for Color Balance, Hue/Saturation, Brightness/Contrast, Curves, Invert and Posterize.
6. Choose Transforms. Try rotating 90, 180, and 270 degrees.
7. Choose Canvas Size. Type different numbers for width and height.
   • Notice the size of the image within the canvas does not change.
8. Choose Scale Image. Change the width and height.
   • The image size changes. If the width:height ratio is changed, the image is distorted.

E-Mailing as an Attachment

• If necessary, copy the lastname.gif and mandrill.jpg photo files to a floppy disk and transfer it to a networked computer with e-mail access.
• Send the files as e-mail attachments in one message to the lecturer with subject line web lab 5.