[argyllcms] Re: nVidia GeForce & deep colour support in Linux

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 28 Aug 2014 09:40:55 +1000

Milan Knížek wrote:

Hi,

> Also dispcal with ColorMunki Photo reports 8-bit precision of video-card
> LUT only.

Dispcal may or may not cope gracefully with higher than 8 bpc
framebuffer depth - some of the the OS API's were missing
an allowance for that when I coded it (ie. MSWin, and the
latest OS X has some strange behavior in this area).
On X11 the depth of the Default Visual is used, since dispwin
creates a window that inherits this from the root window.

The display depth testing is done using the VideoLUT, on the assumption
that the VideoLUT depth is equal to or often greater than the
framebuffer depth (very odd if it is not), and the aim is to test
the calibration precision possible, the video path to the display and
the display capability.

Note that a lot of cheaper LCD displays use an 6 bit panel with dithering
to give 8 bits, while higher quality displays use an 8 bit panel with dithering
to give 10 bits effective, and that you need to use VGA, an (uncommon) dual DVI
connection or Display Port to hope to get more than 8 bits to the display 
itself.

Graeme Gill.


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