[Openicc] Gutenprint team requests CM-off for a print queue be provided as a maintained engineering facility.

edmund ronald edmundronald at gmail.com
Sun May 13 04:41:58 PDT 2012

On Sun, May 13, 2012 at 12:22 PM, Gerhard Fuernkranz <nospam456 at gmx.de>wrote:

> Am 12.05.2012 01:32, schrieb edmund ronald:
>  Why can't every future version of ghostscript for Linux systems have our
>> CM-off switch?
> Well, even older ghostscript versions (e.g. 7.x) already did provide this
> opportunity (via regular Postscript and PDF mechanisms, i.e. either by
> turning the UseCIEColor flag off, and/or by setting the DefaultXXX color
> space resources to /DeviceXXX (i.e. to identity), which disables the
> remapping of /DeviceXXX colors). Therefore it is rather a matter of the
> ...toraster print filters to invoke ghostscript correspondingly (granted
> that they make use of ghostscript at all).
> [ Btw, IIRC, the built-in default value of ghostscript's DefaultXXX color
> space resources did change in the past, so it may be a good idea anyway if
> the ...toraster filters would not rely on ghostscript's built-in defaults,
> but always set up the desired DefaultXXX resources explicitly in oder to
> get consistent results across different versions of gs (and maybe some
> other parameters too, whose built-in defaults may change with version, like
> transfer functions, black generation & UCR functions). ]
> Additionally to "CM-off" it may also be necessary to turn off
> linearization curves in order to print linearization test charts. As far as
> I know, linearization curves are in the current print pipeline not applied
> by ghostscript via transfer functions, but directly applied in the
> Gutenprint driver. So turning them off is a matter of passing corresponding
> parameters to the driver.
> We would assume linearisation to be an issue for Gutenprint to deal with.
And in fact it would be part of the ink-preset XML as this is typically
someting established by a domain expert rather than a programmer.
Personally, for output via Gutenprint, I would expect black generation and
GCR/UCR to become profile-driven in a not too far future, as Gutenprint has
CMYK ability, there is an excellent open-source profiling system available
(Argyll), so I see little reason for anything like that to stay hardcoded
in the longterm.


> Best Regards,
> Gerhard
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