Re: Switching monitor color profile

[Florian Höch <lists+gnome-color-manager hoech org>]

Hi,

Am 07.12.2011 19:01, schrieb Filipp:
> Sorry for the second mail.
> I just tried to use the icc generated by the mac and it worked! (attached)

ICC profiles are platform-independent. So, they can be used under 
different OS with identical results (in the case of display profiles, 
the hardware needs to stay the same of course).

> Now the question is why linux created a different one? even TRC curves
> are different.

I looked at the Apple profile, and I doubt that Mac OS X only used EDID 
info when it created the profile. It contains a detailed 'vcgt' (video 
card gamma table) - this is what gnome color settings dubs 'display 
correction' - that looks like it was generated from real measurements 
(unlike a Mac OS X auto-generated profile for my NEC screen, which 
simply has a linear vcgt). I assume Apple uses some tricks here for 
their own hardware.

The TRC curves are identical to the sRGB TRC (which seems to be true for 
all Mac OS X auto-generated display profiles I've inspected so far).

> And why do linux need a color profile which can not be used for color
> correction at all? :)

It can be used for color correction. Remember you do need a 
color-managed application to use the profile. But it contains no 'vcgt', 
so you won't see any changes in non-colormanged applications.
[ Btw, a vcgt alone is insufficient for full color correction as it can 
only affect the color temperature and TRC; in fact vcgt is not even 
strictly necessary but has some advantages. If a profile contains a 
vcgt, it needs to be used together with the profile to obtain correct 
results. ]

Florian