http://www.stargazin...testpatterns.html shows a smooth transition in the 255-step grayscale.
http://www.lagom.nl/...test/contrast.php shows that I'm seeing more than 16 bit color as well.
The weird colors for faces seems to have been due to a conflict between the Adobe Gamma control panel widget and "Monitor Calibration Wizard". Exiting MCW and using Adobe's tool gives much more natural looking colors, but it's not quite as flexible as MCW in making the fine adjustments.
I'll mess around with this some more when I get time, but as it stands now it looks
much better. (Before highlights on faces were very red.)
Thanks again.
Cheers,
Scott.