GIMP is a free and very versatile photo editing program and easy to operate thanks to the Dutch user environment. Adding effects, adjusting shades, editing colors, using layers, cloning, etc., it's all possible. In a recent comparative test by Computer!Totaal, GIMP was awarded the Redactie TIP quality mark, making it high time for an extensive workshop.
1. Installation
Visit the GIMP website to download the freeware. A version for Windows, Linux and Mac OS X is available. As soon as you start up GIMP, you will arrive at the Dutch interface. It consists of three dialog boxes. In the main window you can open a photo and you will find the menu bar there. The Toolbox with all common tools is displayed as a separate window. On the right side of the screen is another window containing layers, channels and so on. The advantage of the separate dialog boxes is that you can easily adjust the working environment yourself.
2. Open files
You simply open an image in the workspace. Go to File / To open and find an image using the folder structure. Double click on the file to open it. GIMP supports all known graphic formats, such as gif, jpg, psd, png and tif. It is also possible to drag a photo from Windows Explorer or the desktop to the main window. You can also design an image yourself in the program: go to File / New and determine in pixels or millimeters how big you want to make the image. click on OK, after which a white workspace appears.
3. Make selection
By selecting objects it is possible to edit the part individually. Click on the tool rectangular or Oval Selection and drag the mouse pointer over the desired area. By means of Free selection draw lines around the desired subject. A pleasant method is the magic wand. Selects a contiguous area based on color. You set the accuracy with the rear slider Threshold value in the Toolbox. Hold down the Shift key to expand the selection. This makes it possible to select difficult shapes.
4. Brightness and Contrast
Incorrect exposure can make a photo too light or too dark. In many cases, you can still achieve the desired result by adjusting the brightness and contrast. You can easily improve the quality, especially with photos that show faded colours. Go to Colors / Brightness/Contrast. Two scroll bars appear on the screen. Move the slider back Brightness to the right to lighten the colors slightly. Moving to the left actually makes the colors darker. You can also change the contrast value in this way. You immediately view the result of your adjustment.
5. Correct Tone Range
Adjusting the curves is a good way to correct light and dark colors separately. Open the tool via Colors / curves. On the horizontal axis are the darkest values (shadows) on the left and the lightest on the right, with various shades of gray in between. The histogram shows schematically the amount of each value. Move the line at different points to add dark or light tones to the photo. The vertical axis is used to read how the tonal range has changed after editing the photo.
