[poppler] Postscript native image resolution

[Alex Korobkin]

I've switched from pdftops to pdftocairo three years ago and am mostly
happy with it. It produces consistently good print jobs.

Most serious bug so far is this one for me, where pdftocairo chokes on some
PDFs and hogs one CPU for a very-very long time (I have a background job to
kill it after 30 min). If you have a busy print-server, a couple of such
jobs would take it down.

https://bugs.freedesktop.org/show_bug.cgi?id=82963

Another bug is this one, but it affects both pdftocairo and pdftops for me.
They produce a seemingly good PostScript, but Adobe PS engine in the
printers chokes on it. Adobe never replied to my bug reports.

https://bugs.freedesktop.org/show_bug.cgi?id=79897

On Wed, Jul 6, 2016 at 4:18 PM, Pierre-Luc Samuel <
Pierre-Luc.Samuel at ticketmaster.com> wrote:

> OK I tested with pdftocairo and indeed the result is much better. I'm
> kinda surprised though, I would have thought that pdftops would be more
> specialized and generally better, but it doesn't seem so.
>
> Are there some pitfalls to using pdftocairo for postscript rendering?  Are
> there major differences compared to pdftops that I should be aware of?
>
> Thanks for the info, you guys are very helpful.
>
> Pierre-Luc
>
>
> On 07/06/2016 08:10 AM, Adrian Johnson wrote:
>
>> pdftops does preserve the original resolution. However if the page
>> contains anything that can't be converted directly to PostScript
>> (usually transparency), the entire page is rasterized to a single
>> fallback image with the resolution specified by -r.
>>
>> pdftocairo also preserves the original resolution. In the case where a
>> fallback image is required, pdftocairo will only rasterize the parts of
>> the page that can't be converted to PostScript. So if PDF images do not
>> contain transparency they will always be output at their native
>> resolution.
>>
>> There is a bug open to add support to pdftops for finer-grained
>> fallbacks. But I'm not sure how to handle different color spaces.
>>
>>    https://bugs.freedesktop.org/show_bug.cgi?id=66056
>>
>>
>> On 05/07/16 23:19, suzuki toshiya wrote:
>>
>>> Dear Pierre,
>>>
>>> Sorry for that I'm posting this before testing by myself,
>>> have you take a look on pdftocairo? I remember, when I
>>> convert a pdf to a svg, pdftocairo does not re-rasterize
>>> the embedded raster image, so I expect PS output from
>>> pdftocairo could be better for your purpose.
>>>
>>> Regards,
>>> mpsuzuki
>>>
>>> Pierre-Luc Samuel wrote:
>>>
>>>> Hi,
>>>>
>>>> I've been wondering if there is a feature for pdftops that would convert
>>>> pdf to postscript by keeping the original resolution of images embedded
>>>> in the pdf?  The problem I'm encountering is that my pdfs contain low
>>>> res images that are stretched to be big; pdftops converts them by
>>>> re-rasterizing the low res images so that they look smooth.
>>>>
>>>> The result is that my images now look extremely smooth, but the
>>>> resulting postscript file size explodes.  The issue I have with "-r
>>>> <dpi>" is that the native resolution of my images is about 150 dpi, but
>>>> when using "-r 150", I get reasonable file sizes, but the text sections
>>>> of the pdf becomes barely readable....  I would like to suggest a
>>>> "-nativeimageres" option that would be independent of the existing "-r
>>>> <dpi>" option.
>>>>
>>>> Do you guys think a "-nativeimageres" option is technically possible?
>>>> Could you give me indications where to start, in case I need to look
>>>> deeper into this?
>>>>
>>>> Thanks,
>>>> Pierre-Luc
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>>>>
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-- 
-Alex
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