Re: ColorSync and printing -- Panther (2 of 2)
Re: ColorSync and printing -- Panther (2 of 2)
- Subject: Re: ColorSync and printing -- Panther (2 of 2)
- From: Graeme Gill <email@hidden>
- Date: Sat, 20 Dec 2003 17:34:33 +1100
Chris Murphy wrote:
through the driver/OS. I think the long term solution needs to be, as
John Fieber describes, applications that do their own color management
need to include in the job ticket a request for a null transform by
ColorSync. That way the ColorSync Utility can be configured correctly,
but those settings are ignored on a case by case basis, from those
applications that can do their own color management - and when set to do
so. This is something that we've needed to see happen as soon as
Photoshop 5 showed up on the scene of things. And yet here we are three
major versions later, and it's been something like 5 years ago this
month hasn't it? Or has it been 6 years?
This is exactly what we've done in the Cyclone RIP ever since we
added profile support (many years ago now). There are two magic
"job ticket" tags. One turns off just the color space conversion,
the other turns off the per channel calibration/linearisation.
They were intended for use in calibrating and characterising the
device, but the same idea could be used to allow upstream color
management. The situation is slightly different to Colorsync,
in that Cyclone effectively uses device link profiles, and it
is entirely possible to create a "characterisation" CMYK->CMYK
null conversion device link profile (which is what gets used
when the magic tags are seen by the RIP, or can be used all the
time for a particular virtual printer.)
[Things are not quite so simple in calibrating or characterising
7 or 8 channel devices in their native space, rather than
CMYK-"pseudo native" space, but that is another story...]
Relying on Colorsync to do a null transform when the source
and destination profiles are the same description strikes me
as clever, but a bit obscure, and rather flaky if it's difficult/impossible
to know what output profile is going to be used.
Graeme Gill.
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