How to do perspective transformation in GIMP?

How to do perspective transformation in GIMP?

• Download script-fu perspective-transform-to-rectangle.scm.
• Save it in C:\Program Files\GIMP 2\share\gimp\2.0\scripts (or where you installed GIMP 2)
• Refresh the script by going to Menu Filters -> Script-Fu -> Refresh Script
  
• A new menu item "Script-Fu" and "Perspective Transform to rectangle"
  
• Open a new picture that requires perspective transform
  
• Open Toolbox: File: Windows -> Toolbox
• Select the Path tool. Double Click to open "Tool options". Select "Polygonal" in "Tool options".
  
• Draw a 3-sided path (4 dots).
  Press "Selection from Path" to help checking whether the 3-sided path enclosed the area required.
  The Path must be started with Top Left, then Top Right, then Bottom Right and then Bottom Left.
  You may use Ctrl + mouse scroll to zoom in.
  
• Do the transformation: Menu "Script-Fu" -> Transform -> Perspective Transform to rectangle.
  Note the dialog box fired up.
  
  
  Press OK.
• Here is the result:
  

Source of information: http://w3studi.informatik.uni-stuttgart.de/~zimmerla/allyourbandwidth/perspective-transform-to-rectangle.scm