[Openicc] GoSoC 2011: CPD and Color Management

Kai-Uwe Behrmann ku.b at gmx.de
Wed May 4 23:22:39 PDT 2011

Am 04.05.11, 07:55 -0400 schrieb Robert Krawitz:
> On Wed, 4 May 2011 05:40:49 +0200, edmund ronald wrote:
>> Robert,
>> Do you also distinguish Graeme's states 1,2,3 below in this way for
>> Gutenprint? Or would you place the boundaries differently?
> This more or less matches my own process for tuning a printer: I first
> get the drop sizes right, then the light/dark channels ("channel
> splitting", in my terminology), then gamma and level adjustments.
>> On Wed, May 4, 2011 at 3:52 AM, Graeme Gill <graeme at argyllcms.com> wrote:
>>> edmund ronald wrote:
>>>>  However I do think ink settings ALSO need to be able to exist without
>>>> the profile since the ink settings precede the profile, and since it
>>>> is extremely advantageous to be able to adopt the ink settings from
>>>> some known paper as a quick starting point to work with another paper.
>>>> Ink settings, as we agree do precede profiles, and therefore need to
>>>> be able to exist and be invoked independently of profiles.
>>> Yes. Such a format is needed anyway, to communicate the settings
>>> between the print system and the user and or profiling software,
>>> so that they can be embedded in the profile.
>>> Note that a print system mechanism to enable or disable calibration
>>> and separation is also needed to support print calibration.
>>> In general for something like an inkjet printer with light & dark inks
>>> there are four (reasonably distinct) printer states:
>> 1)
>>> * raw with setting adjustments:
>>>    Raw response of the physical color channels. There are still
>>>    resolution, dot size and screening settings, plus a
>>>    range setting (maximum per color value) involved.
>>>    This state is used so as to be able to determine these settings,
>>>    as well as determine the light and dark channel crossovers.
>> 2)
>>> * separated and adjusted
>>>    The dot level settings are set, and the light and dark channels
>>>    have been combined and crossed over to create the set of
>>>    logical device color channels. There are settings and/or tables
>>>    that have been created to do this.
>>>    This state is used to create calibration curved.
>> 3)
>>> * calibrated, separated and adjusted
>>>    The logical device color channels have had calibration
>>>    curves applied to them.
>>>    This state is used to create profiles.
>> 4)
>>> * Profiled, calibrated, separated and adjusted
>>>    The device ICC profile is used to convert incoming
>>>    colorspaces to the devices colorspace.
>>>    This state is the normal end user printing state.
>>> To setup a printer, you need access to all of these states, not just
>>> profiled/not profiled.

Could you please make a recommendation for these four choices and give 
each a unique name? So we could recommend that to all print driver vendors 
on the OpenICC wiki. They can then place these options inside their PPDs 
or whatever and each time this hits a conforming driver it does the right 
thing for your calibration business.

kind regards
Kai-Uwe Behrmann
developing for colour management 
www.behrmann.name + www.oyranos.org

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