[Openicc] Gutenprint mission as Linux moves towards color managed workflows

[Till Kamppeter]

On 05/13/2012 12:53 AM, edmund ronald wrote:
> Gutenprint has provided general print services for Linux users, but it
> has also acquired a constituency of print professionals who use
> externally color-managed workflows to drive legacy hardware. A typical
> use of a professional externally color-managed workflow is "Photoshop
> Manages Colors" driving a Linux printserver where an external instance
> of Photoshop effects the color conversion to deviceRGB by means of
> Adobe's CMM, and a user-supplied profile.
>
> We understand the aspiration of integrated seamless color management
> as proposed by the members of OpenICC. We too have subscribed to this
> effort to provide better color for desktop Linux users. However, we
> have responsibilities to our historical constituency, and we cannot
> require existing users to abandon their workflows on the promise that
> future Linux color management will magically replace decades of
> proprietary development.
>
> Therefore, we believe that any new print solutions that we support
> should *also* fully enable the historical CM-off print queues
> as these are important for our existing userbase. These are also essential
> for our contributors  as engineering and diagnostic tools.
>
> If the new code requested for color-management support does not
> integrate the functionality of the old, then those new developments will be
> relegated to our spare time, as our main effort goes into supporting
> the existing users and providing drivers for new hardware.

What we need here then is a standardized CUPS filter option (like there 
are already options as "number-up", "page-ranges", ... in the CUPS 
filter system) to turn off color management. It could be a boolean 
option named

    color-management

which is set to "on" by default and sending a job with the command line 
option or IPP attribute

    color-management=off

would execute the job with the normal filter chain but all color 
management being turned off.

Supplying this option makes CUPS simply add "color-management=off" to 
the fifth command line argument of all filters it calls, so the filters 
could react appropriately.

The option default can be also changed with an entry in 
/etc/cups/printers.conf (which can be generated by the "lpadmin" command.

On Linux systems these are all filters calling Ghostscript, which means 
gstoraster (ghostscript package), pdftops (cups-filters package), 
foomatic-rip (foomatic-filters package). They are all under my 
maintainership and I would add the option without problems. I would also 
contact free software driver developers to add the option if needed.

Richard, could you help me to get the "color-management=off" option 
correctly implemented in the mentioned CUPS filters? Thanks.

For Mac servers we will need to contact Mike Sweet, as filters of the 
Mac's proprietary PDF workflow will have to get changed.

It would be also very easy to add a checkbox option to any printing 
dialog which makes the jobs being sent with "color-management=off" or 
"color-management=on" depending on the setting. I would call it 
something like

    Turn off color management (for calibration)

and put ity into some "Advanced" group. But this has to be decided by 
the desktop UI designers.

    Till