First, I am using a Canon Pro 100 and I have the driver for the Pro 10,
I do not have Qimage ONE or a Mac. So Let's just say I am giving some hints and thoughts until one of our MAC and Q-1 experts show up.

Number one reason I would not be able to get the Overdrive 1200 would be if I was using the XPS driver. That does not seem to support overdrive.
So try the regular driver and it should work.

Second:
You have to turn on Overdrive using the little drop down arrow. It is not automatic.

Give that a try. Let us know.... and Mike otr Andrew will get on it.

What paper are you using? Might make a difference.

Fred

Overdrive is a feature exclusive to Qimage Ultimate; one that can boost the data going to the driver beyond that of the driver itself.  It is meant for specialized printing such as lenticular prints or prints that are to be viewed under magnification and doesn't make a visible difference for normal photo prints.  So overdrive isn't really in the wheelhouse of Qimage One.  What Fred was showing in that last post is that in Windows, you can actually get the driver to run at 1200 PPI native resolution using the "Prevention of Print Data Loss" feature.  As far as I am aware, that feature is not present in the Mac drivers so you'll likely be running the driver in 600 PPI which is usually what is recommended for photo prints.

Keep in mind that this can be a source of confusion for some, since DPI and PPI are not the same thing.  If you select high quality in your driver, your printer will still be running at its highest DPI setting even if your software outputs 600 PPI: for Canons, the printer is running at something like 4800x2400 DPI.  600 PPI is a good standard for data going to the driver, however, because the printer can't reproduce full color detail at its 4800x2400 print DPI since it can only produce a limited number of colors for each printer dot at 4800x2400 DPI.  By the time you get to that 600 PPI input image, you have 32 printer ink dots to work with, hence by dithering those 32 dots, you can reproduce a reasonable color range at 600 PPI.

Simply put, you should probably be printing at 600 PPI for photo prints.  1200 PPI is more for prints that are examined under "scrutiny"... read that as "magnification".

Regards,
Mike

"Color accuracy" may be a difficult term to define.  The overall accuracy of the colors in the image isn't likely to change from "photo" to "best photo" just looking at the print at normal viewing distances.  But if the original image has enough pixels to work with and the paper can handle the higher DPI, higher DPI necessarily means greater accuracy.  It won't however necessarily mean the overall color of a red fire engine will be a more "accurate" red at higher DPI.

Mike