[Openicc] Changing the display whitepoint using the VCGT

[Chris Murphy]

On Apr 27, 2011, at 2:16 PM, Richard Hughes wrote:

> On 27 April 2011 20:18, Chris Murphy <lists at colorremedies.com> wrote:
>> Although I regularly see the commercial products with colorimeters unpin the blue channel maximum...
> 
> Interesting, thanks.
> 
>> Let me know if it makes sense to consider that and I'll do some testing - maybe the user boots into Mac OS X, the display profile is autogenerated, they put that profile up on a network volume or USB stick, reboot to Fedora and install that profile there. Seems like it would work, but I haven't tried it.
> 
> Ohh, colord is cleverer than that. It already searches for existing
> color profiles on hfs+ disks for the pre-cooked apple profiles for the
> machine, and even on fat32 and ntfs partitions in case the user has
> profiled it in windows. The user just has to override the
> auto-generated profile with the OS X one.
> 
>> What is reading the vcgt tag and applying that curve to the video card LUT? Is that colord's responsibility?
> 
> colord is just a simple dumb daemon -- it doesn't even known what a
> display device looks like. gnome-color-manager creates the xrandr
> device, and then creates / assigns it a profile, which is then applied
> again by g-c-m if the colord rules match. It's a pretty elegant design
> really, as it leaves the session to apply policy in the right place.
> See http://colord.hughsie.com/faq.html#gcm for all the logic.
> 
> If you want to test GCM and colord without breaking your system, I can
> easily put together a Fedora live CD, as it would basically be Fedora
> 15 and an updated version of gnome-color-manager.

I have F15 beta2 running in vbox 4.06, and I'm familiar with yum and rpm so you don't need to go to the trouble of a full CD. But if there's a specific command to run to get gcm and colord updated, that would be useful and I'll see if I learn anything. I'm pretty sure the current beta is running colord 0.1.1?

Chris Murphy