Re: Re. inkjets: An open letter to Tom Lianza and Lars Borg
Re: Re. inkjets: An open letter to Tom Lianza and Lars Borg
- Subject: Re: Re. inkjets: An open letter to Tom Lianza and Lars Borg
- From: Jan-Peter Homann <email@hidden>
- Date: Mon, 19 May 2008 14:10:35 +0200
Hello Lars, hello Tom, hello list
As Now after X-Rite also Adobe is active at the colorsync mailing list
concerning colormanagement for the print path, I want to share some
thought about the directions the problems could may be solved. Parts of
this mail i send to Tom Lianza ten days ago:
***
I think the ICC is the only place, where the solution for the problem
can be solved.
From my point of view, the problem can´t be solved by only defining an
colormanagement UI for the printer driver.
We need also clear definitions how the colormanagement functionalities of
application->OS->printer driver interact.
If we are talking about an ICC based certification program for the
colormanaged print chain, we need definitions and test tools for:
1) how should applications create and tag print data (incl. rendering
intent and info for blackpoint compensation BPC )
2) how should the OS transport the tagged print data to the driver
3) how should profiles attached to printer driver settings
4) how should a printout with no colormanagement be done
5) how should tagged data be colormanaged in the printer driver
In several scenarios, we need also the alternative to do the
colormanagement for the print chain on application level (e.g. printing
complex documents including transparencies from InDesign)
In this case, we need a defined mechanism, that the application is able
to read out the profile from the current printer driver setting.
Also in this case, the application must "sign" the print-data, that the
OS and printer-driver DO NOT colormanage the print-data.
Concerning the certification procedure, I would recommend that the ICC
host documents how the certification should be done and the test tools
do this.
The main control steps of the certification should be free available to
the enduser from the ICC. This makes it possible to use this tools for
analysis of colormanagement problems in the print chain.
As body for certification I recommend a cooperation of Adobe and X-Rite.
This Adobe / X-Rite certification would be based on vendor neutral
procedures and test tools free available from the ICC.
Lets go a little bit deeper about the possibilities:
1) how should applications create and tag print data (incl. rendering
intent and info for blackpoint compensation BPC )
Applications should either create a tagged bytemap for printing or a
PDF-file. The print file needs also following meta-information
- print data should be colormanaged at printer driver
- print data should NOT be colormanaged at printer driver
2) how should the OS transport the tagged print data to the driver
2a) The OS it self should just transport the data generated by the
application without tagging content or without doing any
colortransformation.
2b) The OS is able to render PDF-data to a bytemap for the printer
driver. In this case the OS should:
- read out the profile from the printerdriver setting
- Render the bytemap to the profile of the printer driver setting
- Sign the rendered bytemap, that it should not be colormanaged by
the printer driver
2c) The OS should provide a communication layer between printer driver
and application. Based on this, the available driver settings are
choosable from the application and the application can read out the
associated printer profile.
The complete colormanagement is for the printout could be done by
application. The print-data is signed that no further colormanagement is
applied by the OS or the printer driver.
2d) the OS should define meta-data for the print data, which stores
informations if and how colormanagement for the print-data at
application-level or on OS-level have been already applied.
If the user want, this meta-data can be outputted as a control slug
through the printer driver.
3) how should profiles attached to printer driver settings
The profiles to printer driver setting should attached through the
printer driver and not through the OS. But the printer driver must have
the ability to communicate through the OS which profile is attached to a
setting.
4) how should a printout with no colormanagement be done
The printerdriver should be able to read out the meta information in
print-data, that this printout should not be colormanaged at printer
driver level.
**
More needed functionalities for the printer driver:
The printerdriver should be able to deliver his printing ability through
the communication layer of the OS to the printing application:
- Which kind of data could be printed incl. colormanagement:
- Bytemap only
- PDF without transparencies, overprinting and spotcolors
- PDF with transparencies, overprinting and spotcolors
The printer driver should also able to print a control slug containing
the meta-information from the print-data_
- Colormanagement on application level: No, Only tagging, complete
rendering for the driver settings incl. profile and setting name
- Colormanagement on OS level: No, complete rendering for the
driver settings incl. profile and setting name
- Colormanagement through the printer-driver: No incl. driver setting,
********************************************************
The certification would have three levels:
1) Certification of the OS
- handling meta-information in the print-data
- communication-layer between print-driver and applications
according settings and profiles
- ability of rendering PDF print-data
2) Certification of the printer driver
- possibility of association of driver settings and profiles
- communication with the OS about settings and profiles
- ability to printout the meta information of the print-data
- possibility of rendering and colormanagement (only
bytemaps or also PDF)
3) Certification of applications
- Possibility of communication with printer-driver through OS
- Possibility of creating meta-information for the print-data
********************************************************
How much work is it for realization ?
- Every OS and every printerdriver is able to print bytemaps today
- MacOS X is using PDF as formt for print-data and also several
OpenSource projects are going in this direction
- PDF is standardized as ISO 32000 and defacto vendor neutral
- a lot of applications are either able to output bytemaps or PDF
The work what should be done is to define a communication layer between
printer driver, OS and applications and also a format for metadata
embedded either in Bytemaps or PDF-files for printing.
This could ideally be proposed by Adobe, coordinated with other vendors
at the ICC and be integrated into the ICC specs
*****
What would be the advantages for the vendors
- much less support for color problems in the print chain
- optimal infrastructure for prosumers and graphic arts professionals
- Optimal infrastructure to use entry level spectrophometers and
calibration / profiling solutions
What would be the advantages for the enduser
- Reliable workflows through certified applications, OS and printer drivers
- transparent printouts with control slug showing all the
meta-informations concerning color
- Much easier and more reliable usage of standard profiles provided by
the printer manufacturer or individual profiles
- The same image or PDF printed from different applications looks the
same in print !!!
************************
Hopefully, this letter provides some useful ideas to the graphics arts
community
Regards
Jan-Peter
Lars Borg wrote:
Edmund,
The most useful would be an end-to-end test, not a by-component test.
As others have noted, this is difficult.
Can you propose how this should be done?
In particular, can you propose robust pass/fail metrics that are universally
accepted?
--
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homann colormanagement ------ fon/fax +49 30 611 075 18
Jan-Peter Homann ------------- mobile +49 171 54 70 358
Christinenstr. 21 ------ http://www.colormanagement.de
10119 Berlin -------- mailto:email@hidden
*********** Neue Adresse / new adress ************
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