---How to Straighten a photo using GIMP---- Run GIMP Load your photo: drag & drop Landscape orientation is default but if your photo orientation is portrait, a dialog box will appear "Rotate name.jpg?" so click "Rotate" which makes it show in portrait mode. Press Shift-R to bring up the rotate dialog Use the angle box to rotate appropriately (example: to make horizon horizontal) Click "Rotate" dialog button to finalize your choice. This button is misnamed (your image already appears rotated) and should be named "Accept" or "Finalize." Press Shift-C to get a crop tool: plus symbol and knife. Click & drag to create your cropped image, to eliminate the four triangular checkerboard boundaries. The image crop box now looks OK, but still needs to be finalized. Press Shift-C >>again<< to make the crop happen. Click File::ExportAs to your newname.jpg photo.