[argyllcms] Re: hplip printer driver and color management

On Wednesday 27 August 2008 01:45:04 am Kai-Uwe Behrmann wrote:
> Am 27.08.08, 09:28 +0200 schrieb Geert Janssens:
> > [[For those who don't know: hplip is the open source printer driver
> > project that supports most HP printers on linux.]]
> >
> > Continuing my quest for a new printer, I asked the hplip team how their
> > printer driver deals with color management. You can read the "full"
> > conversation here:
> > https://answers.launchpad.net/hplip/+question/36564
> >
> > After about two months, I finally got this answer:
> > > What printer are you using?
> > >
> > > HPLIP does not support using other ICC profiles.
> > >
> > > However most printer models are able to be color calibrated (not all
> > > models are supported however).
> > >
> > > Hope this helps.
> > >
> > > Aaron
> >
> > I need some help in reading this correctly.
> >
> > > HPLIP does not support using other ICC profiles.
> >
> > This part seems clear: hplip is not CM aware.
>
> Thats wrong. hplip can use CM by the means of CUPS.
> No ICC does not mean no CM. We have to talk explicitely about ICC style
> CM in this context or get easily confused.
>
> > > However most printer models are able to be color calibrated
> >
> > I have no idea how this would work, and how this would impact a colour
> > managed workflow. Would it help to get predictable print results ?
>
> In the CUPS documentation:
> http://www.cups.org/doc-1.1/spm.html#5_1_3

I have asked on various printing related forums and my impression is that 
there are currently no open source *toraster filters in CUPS or from other 
sources that support the use of ICC profiles via the cupsICCProfile attribute 
in the PPD files or when passed a device profile with the --cupsICCProfile 
command line argument.  Looking at newer example PPD files like those for 
GutenPrint 5.2 there are cupsICCProfile entries but these always point to a 
location that does not exist on most *nix machines and appears to be Mac OS/X 
specific.  

In addition, a new pdftoraster filter is being developed for CUPS by a group 
from Japan.  The reason this is being developed is that at some point the 
standard file type used for printing for *nix systems will be changed from 
PostScript to PDF and the new Common Print Dialog (CPD) that is being worked 
on will only accept PDF files.   I have looked at the code for this filter and 
CPD and both are using poppler to do the pdf to raster conversion.  Poppler 
does not follow the PDF specification and has no support for ICC profiles and 
treats all "CIE based" (from the PDF spec - this includes ICCBased) objects as 
being in the target devices color space (IE. no color management is performed 
and all conversions like RGB to CMYK are done using generic routines).  It 
appears that poppler was selected because it is the only available open source 
library that will do PDF to raster conversions.

As far as I know there are no printer drivers which use the cupsColorProfile 
attribute.  I know that this is true for the GutenPrint drivers.   This 
attribute is for doing some type of color management that does not envolve ICC 
profiles.  But what this is exactly is not documented and this is likely 
intended for driver specific uses.  

To sum up CUPS has hooks for implementing color management using ICC profiles 
but none of the existing software in the printing chain uses these hooks on 
any platform other than OS/X and in fact the hooks appear to have been 
designed specifically for OS/X and ColorSync.  

Hal

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