Bug#847462: the problem is with CUPS
On Sat 04 Mar 2017 at 21:06:56 +0200, Martin-Éric Racine wrote:
> 2017-03-04 20:43 GMT+02:00 Brian Potkin <claremont102@gmail.com>:
> > On Fri 03 Mar 2017 at 20:28:56 +0200, Martin-Éric Racine wrote:
> >
> >> 2017-03-03 18:25 GMT+02:00 Francesco Potortì <Potorti@isti.cnr.it>:
> >>
> >> > This apparently has to do with the old problem of cups-pdf converting
> >> > PDF to PS and back to PDF.
> >> >
> >> > I have an old Ubuntu Lucid installation where the problem does not
> >> > exist.
> >>
> >> Debian and Ubuntu both briefly used a patch (around version 2.5.1
> >> IIRC) that bypassed the pdf2pdf filter. It worked well for simply
> >> passing documents that were already in PDF format over to CUPS for
> >> output to a PDF spool. However, it completely broke CUPS-PDF's
> >> primary functionality which is to convert arbitrary document formats
> >> into PDF, and it also prevented users from further manipulating the
> >> documents via CUPS-PDF's configuration file options before outputting
> >> them to the PDF spool. This resulted in complaints from users who
> >> depended upon these features, so I removed the patch.
> >
> > The fullest discussion of this I know of is at
> >
> > https://bugs.launchpad.net/ubuntu/+source/cups-pdf/+bug/820820
> >
> > Users should take note of the comment:
> >
> > > The reasons for not skipping this step are known to you
> > > (it will severly impede the functionality of CUPS-PDF).
> > > Furthermore, once again, CUPS-PDF is not meant for
> > > processing PDF-input (i.e., it is not meant to be a
> > > PDF-manipulation tool).
> >
> > However, cups-pdf is still seen as a general "convert something to a
> > PDF" utility. At one time it might have served that purpose, but not
> > now. Both text and PDF input produce a below-standard, non-searchable
> > output. There is a case for clarifying its purpose as a cups-filters
> > plus backend method for getting a decent quality, searchable PDF from
> > PostScript input only. (Okular produces PostScript; Evince doesn't).
>
> As far as I can tell, the reason why the quality of the output has
> varied over time is because the quality of Ghostscript itself has
> varied a lot.
>
> There might be better filters than Ghostscript we could call to handle
> the generic document conversion step. However, that's entirely
> upstream's decision.
I'd agree that any decision about the direction the software takes is
one for upstream. Hopefully, changes in the Debain printing system will
be taken into account.
Meanwhile, I've implemented my own "print to PDF" system. Don't worry,
it doesn't yet rival cups-pdf!
--
Brian.
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