[Openicc] printer, driver, IPP, ICC- profiles

[Jan-Peter Homann]

Hello Kai-Uwe and all,

You are right, that it is may not easy for all thinkable use cases, to 
manage the relations between Gutenprint settings, media settings and 
printer ICC-profiles and the IPP protocol e.g.

1) Printer Colormanagement Client Side
What happens, if colormanagement for the printer is done at the client 
side and DeviceN data is send through IPP to the printer ?
So far as I Mike understood, this could be realized as following:

- printer profiles and their relations to media settings are handled 
server side
- the client can download the printer profile for a given mediasetting 
(eg. MyPhotoPaper 1440 DpI) from the server
- the client does the colormanagement and sends PWG rasterdata for 
"MyPhotoPaper 1440 DpI to the server
- The question is now: how gets Gutenprint its internal setup for "My 
Photopaper 1440 DpI ?

For the described workflow, printer profiles must be installed at the 
server, before the client downloads the profile from the server.
As Gutenprint is part of the server, we would need a workflow, where 
Gutenprints looks first to the IPP mediasetting, if there is an 
associated printer profile with embedded Gutenprint settings. If yes, 
Gutenprints extracts the settings and uses them. If not, Gutenprint uses 
an internal standard setup (e.g. Photopaper 1440 DpI)

2) Creating Printer Profiles with embedded Gutenprint Settings an IPP 
mediasettings
Most High-End print solutions have today an integrated profiling 
application to handle testchart printing, measuring, icc printer profile 
creation and handling of metadata for the relation between internal 
driver setup, mediasettings and ICC-profile.

If we have on the same machine running
- The IPP server
- Gutenprint
- Argyll
it should be not a big task to create some kind of wizard to:
- choose an IPP mediasetting and associated Gutenprint setting
- store the settings temporarly
- print the testchart
- measure the testchart with Argyll
- calculate the ICC-profile with Argyll
- embed the stored IPP mediasettings and Gutenprint settings as metadata 
into the printer profile

3) Downloading and Installing new printer profiles and IPP media 
settings on the server
If all printer profiles have embedded IPP mediasettings, we need a 
mechnism to extract this setting from the ICC-profile, after they have 
been downloaded and installed.

*************
Mike:
Do You think it makes sense, when the IPP printing community registers 
at the ICC an dictType Metadata tag for IPP mediasettings / profile 
selectors ?
**************

In my eyes, such kind of registration would make a lot of sense, as we 
have the first time a mechanism for defining the relation between 
mediasettings and printer profiles in standardized way (vendor and 
system neutral) inside ICC printer profiles.

In a later step also the IPP specifications could make use of this 
mechanism.

Next week, we will have an ICC meeting in munich, and it would very 
helpful to collect statements from the community if the registration of 
dictType Metadata tag for IPP mediasettings / profile selectors makes sense.


Best regards
Jan-Peter












Am 26.01.12 09:06, schrieb Kai-Uwe Behrmann:
> Am 25.01.12, 12:16 -0800 schrieb Michael Sweet:
>> We can choose to pass calibration data to Gutenprint, perhaps through 
>> ICC profile metadata, but that doesn't solve the general profiling 
>> case and requires a special app to profile just for Gutenprint.
>
> It would be possible to standardise on a meta data tag for ICC 
> profiles. However, how can a profiling application know that this tag 
> is feeded to the rastertoprinter filter? Can a *toraster filter 
> advertise inside the IPP protocoll that it is potential to do so? (I 
> remember fuzzy *toraster was in CUPS a member of a one way chain.)
>
>> We can also choose to support an uncalibrated 16-bit DeviceN space 
>> where 0 means no ink and 65535 means 100% ink (for each color). This 
>> supports having a general profiling application and is not 
>> driver-specific.  And certain key information (such as number and 
>> type of colorants) could be supplied as PPD keywords for the 
>> Gutenprint driver ("this is a 7-color printer with C, LC, M, LM, Y, 
>> K, LK inks") which would take care of the initial defaults when 
>> working with standard colorants for the printer.
>
> I am afraid such 7/8-channel profiles will currently be very large. 
> ICC has no mechanism to define C+LC->combinedC conversions in order to 
> store a calibration in smaller tables. The profile must currently 
> contain a table from all source channels to the destination channels 
> and back for the inverse table. We get for a 8-channel by very poor 9 
> grid points
> 134,217,728 table points * 3 PCS channels. Thats for one table. Add to 
> that a different perceptual and relative colorimetric flawour and we can
> currently take that as a theoretical thing.
>
> In the ICC are various ideas discussed to solve the size issue for 
> n-channel ICC profiles. But none is actual implemented in a real world 
> CMM.
>
> However I find your idea very interessting. In case IPP defines some 
> way to print uncalibrated n-channel, it will be used once ICC has 
> overcome its n-channel issues.
>
> kind regards
> Kai-Uwe
>
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