[Openicc] Print and monitor Color Pipeline

[Leonard Rosenthol]

On Wed, Jan 26, 2011 at 10:05 PM, Jan-Peter Homann <
homann at colormanagement.de> wrote:

> 2a) Old School way to print is creating PostScript and using a RIP like
> GhostScript to create a rasterfile. PostScript is not able to transport an
> ICC based document colorspace, but there are ways, to solve this issues
> /especially with Oyranos and/or Gnome Color Manager in the background,
>
>
There are extensions to Postscript for color management including ICC, but
I'd just avoid this and go to PDF...



> 2b) new school is directly to create PDF for the printout. All PDF content
> would be either DeviceRGB or DeviceCMYK with an Output Intent describing the
> document colorspace. Colormanagement will be applied after rasterization.
>
>
ASSUMING that there was no transparency in the content, then you could do it
this way - otherwise, you need to color manage as part of the rasterization.
  Also, if the OutputIntent doesn't match the printer and the document is
CMYK, you could get a 4-3-4 conversion (whihc no one wants).



> 2c) If the PDF-printout is already colormanaged, the embedded output intent
> will be the same as for the printer driver setting. There will be no need
> for colormanagement during PDF rasterization or after.
>
>
And that would be best!



> 3) Complex Mixed color document
> ************************************
> This are RGB or CMYK documents with text, images and vectorgraphics can
> have individually embedded ICC profiles.
> 3a) PostScript must be avoided for the printdata of such documents, because
> handling of ICC-profiles in individual elements is a nightmare in
> PostScript.
>

Yup!



> 3b) Direct creation of PDF for the printstream is a MUST. As a  user also
> expects a correct match to the monitor, the graphics libray in use should
> have the option to rasterize for print out on non PDF/PostScript
> print-worklflows.
> If the printdata is not colormanaged direct by the graphics library, the
> created PDF for the print stream should contain both profiles for individual
> objects and also one profile describing the colorspace of the complete
> document (PDF output intent)
>

You need to watch this, since this is what Quartz does.  And while perfectly
valid, many professional printers will go nuts about having text and vectors
with ICC profiles assigned.  (just sat through ANOTHER presentation, just
this morning, at the Ghent Workgroup where they ranted about this particular
issue).



> If the OutputIntent of the print stream PDF is not identical with the
> ICC-profile of the current printer setting. The PDF-rendering and
> rasterizing should be done firstly to the document colorspace and than to
> ICC of the printer driver setting.
>
>
Nope!   You should follow the rules for PDF rasterization and color
management as defined in ISO 32000.


Leonard
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