IIRC Windows does support 10-bit color, but only in the fullscreen
exclusive mode of various hardware acceleration APIs like Direct3D and
OpenGL. I heard rumors they were working on enabling 10-bit color for the
desktop, but I have no idea whether that's true or what the timeline for
such a change would be if it is.
One thing I have wondered is whether anything actually uses more than 8
bits of the 16-bit RAMDAC values that Windows uses. I was thinking of
modifying dispcal locally to set the LUT directly instead of modifying the
color of the test patches, to see if that gives it access to more than 8
bits on my 10-bit monitor - but that would be a pretty major change
(potentially making the whole process more direct), and I haven't even
checked yet whether dispcal can easily access the LUT setting functions of
dispwin.
