Canon Maxify MB5020 scan above 600dpi

My Canon Maxify MB5020 specification indicates max optical scan as 1200 dpi or up to 19,200 interpolated: However, with drivers installed I cannot select above 600 dpi: 1200 x 1200 dpi optical should be a selectable option, referring to the optical resolution of the CCD cell and mechanical stepping of the motor drive. Is there something I'm missing regarding configuration; or, the specification itself? How can I scan at 1200 dpi?

Question by Jason Sturges on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.