[Openicc] Linux CM ideology, was: meta data in test chart

[Kai-Uwe Behrmann]

Am 28.01.11, 13:24 -0700 schrieb Chris Murphy:
> For the explicit off switch to opt-out, you'll need to consider an 
> "anti-tag" or a special kind of tag in lieu of an ICC source profile 
> that basically means "no color management". I think this is easier to 
> implement for both parties than a separate API.

The net-color spec just avoids multiple colour spaces. Eigther its sRGB or 
or it remains untouched. Thus it can be fairly simple. It is a opt-out 
mechanism.

Please keep in mind that Linux is nowhere as monolithic as osX. We have 
many, many legacy apps, toolkits and Xorg itself, which does not handle 
colour management and does not want to change that in a forseeable future. 
I think its better to focus on how to support applications, which want to 
do colour management __and__ provide a reasonable environment for the 
majority of all others. This reasonable environment is IMO best realised 
as a opt-out system. A opt-in system can well coexist with a opt-out 
system.


Here a comparision of a opt-out and a opt-in system and what IMO it 
means to different projects:

Firefox has an internal model of sRGB inherited from WWW standards with 
few exceptions. A opt-out system would have brought basic colour 
management instantly to the majority of its users on Linux. They have now 
coded their own colour management system.

OpenOffice does not care about colour. So a opt-in system will be 
considerd a huge wast of time. It will be well served by a opt-out system.

A paint application like Krita might use colour management on top of 
OpenGL inside the application. A shared KDE library might help with that 
and with opting out from colour management for its image views. With 
opt-in it is fine as well.

Inkscape might use a colour management aware Cairo. It will opt in on the 
(more or less) toolkit level. No need to think about opting out somewhere.

Blender cares about internal colour management. A opt-out system cares 
about displaying its content as sRGB.

Xine, MPlayer, VLC will instantly look compareable on linux desktops and 
in the show room. You know all those computer sales points with showing 
a movie, but all in different colour casts. A opt-out system would make 
them appear much more consistent.

Xorg decidedly does not care about more than just RGB. It will profit from 
a opt-out system.

ArgyllCMS wants a robust opt-out mechanism to calibrate and profile 
displays. This is done best with a Xorg only window. For a opt-out system 
it has to do something but not that much.

Window managers can garantee that all content is very consistent through 
opt-out. They need to convert all content except for marked regions. A 
opt-in system would be less work, but as well less smart.


kind regards
Kai-Uwe Behrmann
-- 
developing for colour management 
www.behrmann.name + www.oyranos.org