On Thursday, Aug 7, 2003, at 09:08 Europe/Copenhagen, Darrian Young
wrote:
They are one of the few inkjet
manufacturers that take in CMYK data as compared to Epson (RGB), for
example. Example. - Designjet 755, 2500, 5500.
True, but the DesignJet pipeline has several safeguards against a CMYK
workflow, including the UseCIE architecture which is leveraged to
reseparate incoming deviceCMYK (by assigning a ToCIE reference to the
deviceCMYK object).
And, if I recall
correctly (it has been some time since I have looked), even if you take
an HP10 with the bundled RIP to which you can send RGB or CMYK data,
the
default RGB profile does not match the default RGB profile of
Photoshop.
As far as I remember AdobeRGB(1998) is installed. In all fairness Adobe
also allows multiple default RGB working spaces, one of which is sRGB
and another AdobeRGB(1998).
Also, HP advocates sRGB and neither ECI-RGB nor Adobe
RGB (1998), which
is not a particularly optimal working space for offset. Of course it
is
much easier to simply hand-off RGB data and hope that everything comes
out great (no clipping, no loss of gammut, no banding), but the problem
is that invariably people start to ask questions when their beautiful
blues come out flat.
One may argue that sRGB is even less optimal for inkjet presentation
prints where the maximum gamut available is desired. But the DesignJet
pipeline does not impose any hardwired restriction on the addressable
gamut. It is not the case that every incoming RGB object is assumed to
be sRGB which would mean that nothing the user might do would allow the
printing system to address the maximum gamut of the colorant and media
combination.
However, the problem remains that one has to assign defaults to
untagged device RGB or accept a PostScript level 1 RGB to CMYK
conversion . . . ugh. The UseCIE procedure listed above for device CMYK
objects also applies to device RGB objects.
Some years ago when what was then Purup-Eskofot was introducing the New
Age workflow, the developers were scratching their scalps over which
RGB working space to set as default for the CTP system. It's
everybody's headache -:).
I guess the question is whether inkjets should be receiving CMYK,
because in the majority of cases the incoming CMYK is targetted for
newsprint, offset or gravure with ink limit and black generation
behaviours that are not so great on an inkjet system. Which is why
UseCIE procedures allow in-RIP reseparation.
Thanks,
Henrik