[Openicc] Actually getting color managed printing to work

[Till Kamppeter]

On 01/28/2012 10:17 PM, edmund ronald wrote:
> Richard,
>
>   I think the profile stuff happens in CUPS upstream from Gutenprint -
> this is a raster driver which doesn't know about colorspaces. So
> Gutenprint won't be reading profiles. Robert may have something
> different to say.
>
>   My belief, confirmed by today's phone conversations is that CUPS knows
> a lot about profiles though, and performs profile conversions on input
> data when asked nicely.

In case of Gutenprint (the CUPS Raster driver, not the IJS driver) there 
is a rendering step before, pstoraster (Ghostscript), pdftoraster 
(Poppler), or gstoraster (Ghostscript). If you want to have color 
management, it is done on the renderer level and currently you have to 
use a current Ghostscript (9.04 or later) with its gstoraster filter. 
This reads out the ICC profile entries from the PPD and Ghostscript 
applies them (at least for PDF input, I am not sure whether also for 
PostScript input).

I am not sure whether Poppler is ready for doing that, at least I do not 
see any reference to applying the PPD's ICC profiles in the 
Poppler-based rendering filters pdftoraster, pdftoijs, and pdftoopvp 
(all in the OpenPrinting CUPS Filters package, 
http://www.openprinting.org/). So at least these filters need to get the 
ICC profile support added.

In Ubuntu I use gstoraster/Ghostscript by default, so it should be 
possible to make print queues PPD-ICC-color-managed.

    Till