My prints are of poor quality: white stripes / inferior colour.

If the cartridge is low on ink or empty, you can clean the print head one or more times using the cleaning program. You can find this under “Printer Maintenance” (name may vary by printer).

You can also click on the following link, Manual for Canon Pixma printers. This redirects you to the site with Canon Pixma printers. Here you can select your printer from the list and then download the manual. The manual describes how to clean the print heads, how to align the print heads and how you can check the ink levels.