I got the printer model wrong (now corrected to PIXMA MP780) and thanks to itnet7 I found the correct repos(itory).

The steps I used to get this printer installed are these:

as from itnet7 open a terminal and enter...

sudo add-apt-repository ppa:michael-gruz/canon

then...

sudo apt-get update

But for the MP780 which is not in michael-gruz repos, but the iP4100 is and from this ancient website

http://mambo.kuhp.kyoto-u.ac.jp/~takushi/

I learn that the iP4100 drivers work for the MP780, so...

sudo apt-get install cnijfilter-pixusip4100series

and then to get Ubuntu to recognize and configure the MP780, open a browser and use this URL...

http://127.0.0.1:631/

which should open CUPS 1.5.0 administration, click on Adding Printers and Classes then the Add Printer button...

Here you should see all local printers if they are connected and turned on.

Select the MP780 and "continue"...

Then fill in or change the printer information, &c, "Continue"...

Then select Canon PIXMA MP780 - CUPS+Gutenprint v5.2.7(en) for the model, and finally press the "Add Printer" button....

Then You can set the default options and finally hit the button...

Ubuntu should pop up a message about the new printer and it should be shown in System Settings / Printers.

Good Luck!