Re: [Gimp-user] Basic Color Management

2016-02-11 Thread Kevin Brubeck Unhammer 
"Mike Brennan"  čálii:

> GIMP 2.8.14 Windows 7 64
>
> In Preferences -> Color Management I've selected "Mode of operation" =
> "Color managed display"
>
> There's a checkbox: "Try to use the system monitor profile" that I'm
> unclear about.
>
> I've calibrated/profiled my display with ColorMunki hardware. My
> understanding (wrong?) is that ColorMunki installed an appropriate
> profile for my display on the system, and that all output from ANY
> application to the display goes through an OS driver that uses that
> profile. If that is so, my assumption is that GIMP will "use" the
> correct display profile implicitly, without needing to be told to do so.
>
> I do not understand whether checking "Try to use the system monitor
> profile" is unnecessary, redundant, or even harmful.

When you profile your display you get a two-part result:

- a vcgt/LUT part that does white point correction, applied system-wide
  on login (it's often noticable when this is applied, e.g. with
  slightly colder or warmer colours all-round)

- a gamma/hue/saturation part that has to be applied by individual
  colour-managed programs

On Linux, if you have the right setup, programs can query the system for
what file contains the gamma/hue/saturation part – that's the part
that's applied by the "Try to use the system monitor profile" checkbox.
So this should work in e.g. GNOME or KDE if you've selected your profile
in your system colour management settings, but in desktops like XFCE you
have to run a separate program, or select the profile manually from GIMP
settings.

Caveat: I have no formal training in this, please read what the experts
say instead:
https://encrypted.pcode.nl/blog/2013/11/24/display-color-profiling-on-linux/


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Re: [Gimp-user] Basic Color Management

2016-02-02 Thread Gez 
El mié, 20-01-2016 a las 13:54 -0700, Mike Brennan escribió:
> GIMP 2.8.14 Windows 7 64
> 
> In Preferences -> Color Management I've selected "Mode of operation"
> =
> "Color managed display"
> 
> There's a checkbox: "Try to use the system monitor profile" that I'm
> unclear about.
> 
> I've calibrated/profiled my display with ColorMunki hardware. My
> understanding (wrong?) is that ColorMunki installed an appropriate
> profile for my display on the system, and that all output from ANY
> application to the display goes through an OS driver that uses that
> profile. If that is so, my assumption is that GIMP will "use" the
> correct display profile implicitly, without needing to be told to do
> so.
> 
> I do not understand whether checking "Try to use the system monitor
> profile" is unnecessary, redundant, or even harmful.

As far as I can tell from my linux install, marking that checkbox
overrides whatever display profile you selected and uses the profile
installed in your current user.
I'm not sure if other platforms behave the same, but that's how it
works on Linux.

Having selected a display profile from disk doesn't result in a
redundand or harmful adjustment, as it's just ignored when that checbox
is set.

I guess it's easy to check if that's working in your system:
Just set the display profile to none, and mark the checkbox, then flip
between "color managed display" and "no color managment".
If there is a change, then your system color profile is working.
You should get the same change turn on and off the checkbox (and your
monitor display is set to none).
If you set manually the same display profile your system use, turning
on and off the checbox shouldn't make any difference.

Gez.
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