After upgrading to ubuntu 14.10 my MP270 no longer scans. Xsane recognises the scanner but does not scan and give a message "Window is not responding". Simple Scan gives a similar result. Printing still works fine. This has only started happening since upgrading from 14.04. With 14.04 scanning worked perfectly.
Some Canon scanners aren't yet fully supported by sane, especially PIXMA MP devices. (got one myself) However, Canon provides its scanning suite ScanGear MP for Linux. You can download it on Canon's support webiste of your country.
In some countries, including the U.S., the software isn't deployed. So here's the downlaod link from the Canon Switzerland support website.
Download the deb package and install it as you would do with any other. (Install with gdebi, USC, or directly with
sudo dpkg -i <package_file>)
The package doesn't come with a desktop file, so take the one I made:
Name=Canon ScanGearMP Exec=/usr/bin/scangearmp Icon=scanner Terminal=false Type=Application StartupNotify=true Categories=Graphics
Save it as "scangearmp.desktop" in either
/usr/share/applications/ (for all users) or
~/.local/share/applications/ (only for yourself)