[cups] Windows bypasses cups drivers

[Johannes Meixner]

Hello,

On May 19 17:52 Maarten Suetens wrote (excerpt):
> Would there be a way to make the print server re-evaluate the job that it 
> gets from the windows client using specific PS driver and apply its own 
> settings(grayscale) on that job, or would that not be possible.

Everything is possible because the CUPS filtering system
(i.e. what converts data as needed) is not hardcoded
but fully adaptable to any need.

But adapting the default CUPS filtering system could
become a bit tricky.

First:
When the Windows clients submit printing data to the CUPS server
via the SMB protocol, then the recipient on the CUPS server
is not CUPS (i.e. the cupsd) but Samba and then Samba forwards
it to the cupsd.
Usually when Samba gets printing data from Windows clients
it forwards it explicitly marked as "raw" to the cupsd.
But "raw" data is not at all processed by the CUPS
filtering system, see
http://en.opensuse.org/SDB:Printing_from_Windows_to_Linux
In this case you need to change the Samba settings on the
CUPS server to no longer forward printing data from Windows
clients as "raw" so that the CUPS filtering system will be used.

Second:
Likely the default CUPS filtering system will not work correctly
for printer specific data that was made by a Windows driver.
In this case you need to adapt the default CUPS filtering system
according to your particular needs for your particular Windows
driver, see
http://en.opensuse.org/SDB:Using_Your_Own_Filters_to_Print_with_CUPS
Perhaps
http://sourceforge.net/projects/cupsaddons/files/filter-colorfilter/
is already exactly what you need in your particular case.


Kind Regards
Johannes Meixner
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