[Openicc] GoSoC 2011: CPD and Color Management

Robert Krawitz rlk at alum.mit.edu
Wed May 4 04:55:54 PDT 2011

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.

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