Source GScan2PDF Homepage.
Overall, gscan2pdf is a decent application for creating multi-page digital documents from scanned pages, in the PDF or DjVu file formats. It comes with a great, easy to use and modern user interface, as well as support for multiple languages.
To install GScan2PDF just run the following commands via your systems Terminal.
sudo add-apt-repository ppa:jeffreyratcliffe/ppa
sudo apt-get update
sudo apt-get install gscan2pdf
That's it enjoy.