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[cliddell <1476705@xxxxxxxxxxxxxxxxxx>]

Bruno,

To be honest, I don't know what differs between the two tools, as they
both come from Cairo, I assumed that pdftops was just a small wrapper
around the same code as pdftocairo but with the options pre-set for PS
output.

I'm a Ghostscript developer, so I can't really answer specifics about
Cairo - I know about the problems with the Cairo PDF output, as we've
performance problems in Ghostscript with those, and have had some fairly
lengthy (and heated) discussions with Cairo developers on the subject.

And I have helped debug a lot of these problems with the Ghostscript
output, so I can give general suggestions as I did above.

If I had to guess, I would say that pdftocairo is possibly spotting that
the PDF originated as a Cairo file, and is using "inside" knowledge of
how those are constructed to convert it back into Cairo internal
representation, which is then outputs to Postscript - with that level of
extra information, it can probably be much, much smarter about when
there is real transparency that it has to render, and when everything
opaque, and remain in high level form. Whilst, pstops may be doing a
simpler, one step PDF to Postscript conversion.


Ideally, what you'd want to try is (if possible) to keep the "ProRes" (I thought it was "ImageRET") mode, but still tell pdftocairo to use 600 dpi, as you then may get the benefits of more the accurate dot placement, better halftone results, and possibly better color management, whilst keeping the quicker processing of the smaller image data.

It's hard to know without deep inside knowledge, but (again) if I had to
guess, I would suggest that the slightly lower quality halftone screen
is what's causing the slight intensity shift you mention. HP are pretty
tight lipped about these technologies, but I know other such systems
tend to allow the halftoning to represent more shades of the color,
without losing detail (generally there is a trade off: you can
approximate lots of shades, but lose detail, or have great detail, but
very few shades).

Chris

-- 
You received this bug notification because you are a member of Desktop
Packages, which is subscribed to poppler in Ubuntu.
https://bugs.launchpad.net/bugs/1476705

Title:
  postscript printer hideously slow in some cases (pdftops)

Status in poppler package in Ubuntu:
  New
Status in system-config-printer package in Ubuntu:
  New

Bug description:
  With my (old) postscript printer, print a single page can take many
  minutes on some situations. It happens with some PDF files (not all)
  and Firefox printing of Google map, for example. When this happens, I
  observed in system monitor that pdftops is running continuously. After
  some manual PDF -> PS conversions, I see that pdftops inflates the
  file size for problematic cases, but is ok for other files (size
  similar to the original file, or even smaller). I don't know if modern
  Postscript printers can handle this quickly, but it's unacceptable
  here and certainly not an efficient way to print those files.

  So I suspect that pdftops should be fixed.

  For example, I join a problematic pdf produced by Google Map in
  Firefox. I tried many conversions. As you can see, I get a much larger
  file (36 times) with pdftops. It is worse with pdf2ps (and it takes
  longer to process), so replace pdftops by pdf2ps is not an option for
  me. However, pdftocairo quickly produces an efficient file. I have the
  same success if I open the PDF file with Evince and print it as a
  Postscript file. I get a similar file if I print to PS directly from
  Google Map (Firefox). Of course these small PS files produced by
  pdftocairo, Evince of Firefox print flawlessly on my printer.

  See also Bug # 1095498 which I suspect is the same (old) thing, but I fill a new one since it doesn't seem to be printer specific.
  Of course, another workaround could be to use a PCL driver but no one is available for my printer (HP Color Laserjet 2605dn).

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