I'm a newbie too, so take this with a LARGE grain of salt. Go to http://www.mostang.com/sane/.
There you will discover that the driver for the Canon N670U is in beta version and has poor color picture quality.
If you've already bought this scanner it may be a while before you can properly use it. If you haven't bought it yet, check out the support list at Sane and get something already fully supported.