How to automatically rotate a scanned image?
Even if you insert the paper into the scanned carefully. About one degree rotation is left. Is here no way to automatically rotate the scanned image?
I use Ubuntu 14.04
You want to apply the De-skew plugin from Gimp in batch mode. This means you prepare a script, then run it from Gimp in console mode to auto-rotate a number of scanned images in one go. Full instructions can be found here. Note, however, that the plugin's homepage has been moved to https://github.com/gimp-plugins-justice/gimp-deskew-plugin.