Printer Demos vs. The Real Thing

I'm working with an Oki C5400n here, and I don't understand how some
prints look extremely good (especially with the built-in demo picture,
of course), but the pictures I send at very high resolutions (3" by 5"
at 600+ dpi) still look grainy.

Is there some "magic" resolution that lets the printer print non-grainy
pictures?
Is it printing the demo picture with a different, hidden printer?

Any help would be appreciated.

<peter.RemoveThis@mcnabbs.org> wrote in message
news:1133058488.581384.168660@g14g2000cwa.googlegroups.com...
> I'm working with an Oki C5400n here, and I don't understand how some
> prints look extremely good (especially with the built-in demo picture,
> of course), but the pictures I send at very high resolutions (3" by 5"
> at 600+ dpi) still look grainy.
>
> Is there some "magic" resolution that lets the printer print non-grainy
> pictures?
> Is it printing the demo picture with a different, hidden printer?
>
> Any help would be appreciated.
>

In the print driver are you setting the quality setting to best?

Scott