Fixing Perspective: Leaning Buildings

GIMP has a powerful Perspective Tool. Use the Perspective Tool to correct a photo that has leaning buildings or towers or power poles etc. (see Figures 4-20 and 4-21)

Figure 4-20. Leaning building before using GIMP's Perspective Tool

Figure 4-21. The same building after using the Perspective tool. Note that a small amount of the image has been cropped.

The following exercise shows you how to straighten an image. Once you have completed the exercise, feel free try different options in the tool.

To straighten a leaning building, follow these steps:

1. Open your image in GIMP.
2. Click on the Perspective Tool located in the Toolbox (see Figure 4-22).
3. Below the Toolbox are the Tool Options for the Perspective Tool. Select the following Tool Options (see Figure 4-22):
   • Direction: Corrective (Backward)
   • Interpolation: Sinc (Lanczos3) - optional
   • Clipping: Crop to result
   • Preview: Image
   • Guides: Number of lines, try 15
   

   Figure 4-22. When the Perspective Tool is selected, the Tool Options for the Perspective Tool are available.