Straighten a Crooked Photo with The GIMP

We probably all have pictures we took when the camera was not perfectly level, resulting in a skewed horizon line, or crooked object. I'm going to show you how easy it is to correct a crooked photo with the rotate tool in The GIMP. Any time you have an image with a skewed horizon, you're going to have to lose something from the edges of the photo. The sides of the image will have to be cropped to make up for the slanting of the photo from rotation. Since you always have to crop a photo when you rotate, it makes sense to rotate and crop in one step with the rotate tool.

Feel free to save the practice image here, then open it in the GIMP to follow along. I am using GIMP 2.4.3 for this tutorial. You may need to adapt these instructions for another version.