[Openicc] cupsICC on remote CUPS servers Part 2

Jan-Peter Homann homann at colormanagement.de
Fri May 20 01:14:22 PDT 2011

Hello list, hello Kai-Uwe, (Question to Mike and Till at the end !!)
If we have a remote CUPS server, I would recommend, that driver 
settings, ICC profiles and a PPD representing this setup are managed 
centrally at the CUPS server.
This is necessary to make sure, that all user working with the CUPS 
server are using the same setup.
As a result, only the people with admin rights for the CUPS server are 
allowed to install printer ICC profiles with assignend driver settings.

As the CUPS protocol do not allow to pull ICC profiles from the server, 
we have to work with the CUPS PPD dependent mechanism for communicating 
the available colorsetup to the CUPS clients.

Concerning the PDF print spool format, it will be easier to implement a 
color managed printing path, if the PDF print spool format transports 
only the profiles for describing the document colorspace.

In the print chooser (e.g. CPD), the user chooses the cupsICC qualifiers 
(media, resolution) presented through the PPD, which CPS has pulled from 
the CUPS remote server. On CUPS serverside, the cupsICC qualifiers are 
intepreted and the printer profile for pdftoraster is setup through 
through the cupsICC selection process.

Questions to Michael Sweet and Till Kamppeter
- Is this is workflow-proposal, which makes sense for a color managed 
print path with remote CUPS servers from your point of view ?
- If not, what are the alternatives ?

Best regards

Am 20.05.11 09:45, schrieb Kai-Uwe Behrmann:
> Am 19.05.11, 21:25 -0400 schrieb Robert Krawitz:
>> On Thu, 19 May 2011 15:58:57 +0200, Jan-Peter Homann wrote:
>>> I´m not developer, but I´m working regularly together with
>>> developers.  From this experience, the manipulation of pure ASCII
>>> files like a PPD is not something very complicated.  Is it really a
>>> lot of work to create e.g. a basic PPD without color relevant
>>> entries and update the color relevant entries from profile Divtype
>>> metadata, which are installed on on the remote CUPS server ?
> Does CUPS provide an API to manipulate remote PPD files?
> [Please keep in mind a changed PPD will apply to all users of a print
>  queue.]
> Again, it makes sense to deliver a PPD with fixed settings for a 
> desired calibration state, add the cupsICCProfile property and ship 
> and install that PPD with the according ICC print profile. Thats 
> clearly a CUPS server thing useful for vendors like GutenPrint and 
> administrators as they have control of packages or the needed access 
> rights.
> For user configured profiles that makes not much sense as Hal already 
> pointed out, because of the static nature of server side installed PPDs.
>> For Gutenprint, the first part (creating PPD files without
>> color-relevant entries) is no problem.  The rest of it, I'll leave to
>> people with more experience in that area.
>> (Gutenprint's PPD files are all generated based on information in the
>> driver.  Since we added information about which options affect color
>> in 5.2.7, it would be a simple matter to generate PPD files without
>> color information.)
> Then the defaults would apply, which appears to me different from the 
> driver settings that have formed the calibration state during target 
> printing.
> kind regards
> Kai-Uwe Behrmann
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