[Openicc] [Gimp-print-devel] [Printing-architecture] Colour

[Kai-Uwe Behrmann]

Am 14.11.09, 17:11 +1100 schrieb Graeme Gill:
> Chris Murphy wrote:
>> filter, and also ColorSync) to not convert the target. Presently on Mac OS the
>> application of choice is Photoshop, with which we are presently having problems because
>> the No Color Management based PDF spool file has different profiles set for the profile
>> target object, and OutputIntent, causing ColorSync to color manage. It autoconfigures
>> newer print driver settings correctly, but the PDF spool file is malformed, so we get a
>> converted profile target.
>
> Yes, basically this is a really dumb API for turning color management off.
> The right way to do it is to have a flag that turns color management off,
> rather than relying on the software to figure out what profile is being
> used for the end device, and labeling the file as already being in that
> space. It's easy to demonstrate that this is sematically incorrect -
> if you were to spool the file and then replay it after the device
> profile has been changed, it will print incorrectly.

I am not familiar with such a flag. So I may ask, where does this apply to 
which API? The print API while sending data which gets converted to PDF?
The CMS, which is responsible to do the colour conversion or has in that 
special case to omit a conversion? ... or the spooling system? ...


Following  Chris' explanation, a print system "correctly" supporting 
Device(RGB/CMYK/GRAY/N) in PDF/X-3 will have a path to pass all colour 
management conversions unaltered. Could this become a simple means of 
implementing Mike Sweets less is more scheme of hiding CM controls? 
It would mean generate according targets and send them through CPD as file 
to the selected printer.


Still unresolved is the per paper ICC profile selection. To solve that 
point CPD would be in need to add custom entries to non traceable 
variables. These are mainly media and ink types which a driver has 
currently no way to know of in a programatic manner.


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