[GSoC] KWin colour management

Kai-Uwe Behrmann ku.b at gmx.de
Wed Mar 21 07:39:29 GMT 2012

Am 20.03.12, 21:17 +0100 schrieb Thomas L├╝bking:
> Am 20.03.2012, 20:12 Uhr, schrieb Martin Graesslin <mgraesslin at kde.org>:
>> A fully  color corrected compositor seems feasible to me
> I'm atm. not even sure about that.
> I might be utterly wrong, but my impression is that the xvidmode extension 
> can correct screens (eg. xcalib loads icc profiles), so a screen wide color

xvidmode gamma ramps are per channel curves. These are very limited 
compared to ICC based colour correction. Those gamma curves provide better 
gray balance and potentialy white point adjustment. But they do not 
describe colour primaries shifts or other more complex distortions. Gamma 
curves must be taken into account for ICC profiles. But detailed 
characterisation of device colorimetry happens usualy in ICC profiles.

> correcting compositor would be only required to fix multiscreen (not 
> multihead) setups which i frankly consider no case either, because a full 
> correction would just mean to restrict the WG screen to the SRGB one

The X Color Management spec requires per window colour correction for base 
line implementations. Thus it is possible to specify an source space other 
than sRGB.

> (yesno?!), what doesn't much sound like a great achievement to me (and is 
> simply no case in at least the professional context. You don't purchase _one_ 
> WG screen to use it -restricted- alongside your SRGB screen, but just 
> purchase two WG screens and give away the SRGB one to one of your employees 
> at home or whatever)

exactly. Thats why opting out of colour management and being able to 
specify a intermediate colour profile is a good thing.

> Cheers,
> Thomas

kind regards
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