[Openicc] ICC Profiles in X Specification 0.4

[Kai-Uwe Behrmann]

Am 25.03.10, 10:44 -0000 schrieb Richard Hughes:
> On 25 March 2010 10:09, Kai-Uwe Behrmann <ku.b at gmx.de> wrote:
>> * multi monitor support and its relation to Xinerama/XRandR
>> * server side colour management
>
> What is the benefit of this to applications?

First the benefit to users is a consitent desktop. Laptops, wide gamut 
monitors and so on will much better agree in their appearance then without 
colour corrections.
For applications it means their content appears in a consistent 
environment of widgets and other areas on the desktop.

>> * colour space tagging of window regions
>
> Again, what's the high level usecase? Two use cases for me are, for example:
>
> * Inkscape color corrects the active work area only using lcms to
> convert an embedded image with a profile to the display profile
> without a compositing window manager on low performance hardware
> * A compositing frontend color corrects un-color-corrected areas in a
> screen area on a high performance desktop on a high gamut LCD screen
>
> A use case is the high level "what you want to do" rather than the
> "how I'm doing it".

Performance. This path has minimal impact on CPU usage. Its similiar to 
1080p video decoding on CPU versus GPU. Only colour correction is more 
efficient on the GPU than video decoding from what I can see.

>>> In this way it would be a bit like a firewall, where you only 'punch'
>>> out regions of the desktop which are already color managed. All we
>>
>> Yes, thats what the compiz colour server plugin only does.
>
> So why bother uploading profiles to the xserver? It looks to me all
> the source profiles are being uploaded. What atom name are you using
> to tag windows that already have done early color-correction? It seems

It sets a region with a md5 hash of zero. UUID is not used any more.

> version 0.4 of the specification should just introduce this atom name
> and _suggest_ that applications that are using _ICC_PROFILE use this
> atom on each window they are color correcting themselves. Certainly
> leave _ICC_DEVICE_PROFILE out of 0.4 until at least one other person
> agrees it's a good idea.

Thats not good. Elder applications will double colour correct this way.


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