[Scribus] PDF generated from Scribus doesn't print right

[avox]

Gustavo Homem wrote:
> 
> On Tuesday 27 March 2007 20:12, avox wrote:
>> >
>> >> printer (8.5 x 11 inches) but for what it is worth, when asked to
>> print
>> >> just page 1, Acrobat 7 did print out the first page correctly (the one
>> >> that
>> >> is shown pixellized in your PNG example)
>>
>> How did you produce this? Scan three images, convert those to PDF,
>> put PDFs into imageframes in Scribus, produce PDF?
> 
> I was given a 3 page PDF file, but I wanted to impose the pages as two
> pages 
> per sheet and partially resized and cropped (with an image frame).
> 
>>
>> Dont Do That!
> 
> I knew someone would say this :-)
> 

Then why did you do it? :-)

I still think that the original 3 page pdf contained bitmap data instead of
vectors, which is poor quality.



> I did not scan anything. So, the input format being PDF is out of the 
> equation, optimal or not. 
> 
> Plus, Scribus allows me to import PDFs into a document and then generate a
> PDF 
> from there: seems to be a valid Scribus use case.
> 
>>
>> Bitmap images are extremely sensitive when being scaled to near 100% but
>> not exactly 100%.
> 
> Why does it only affect printing then?
> 
> Onscreen both sides look perfect, and on paper one of them looks awful.
> It's 
> so different that I doubt it is only "sensitivity".
> 

It looks pretty awful to me when I view it in Acrobat Reader at 400% (which
should give an average printer resolution)



> Furthermore, if I print to postscript from Acrobat and convert back to PDF 
> with ps2pdf it is fine again.... the "sentivity" vanishes.
> 
>> That's why you scan at least at 400 dpi if your output is 300 dpi.
>>
>> In your case the image on the first page is probably scaled twice: once
>> when the PDF is placed
>> (likely at 99,5% or 101% or someting similar) and the second time when
>> the
>> page is output.
>> To avoid this, use the images (tiffs?) you get directly from the scan
>> process and place those
>> in Scribus. If you need to scale, avoid percentages near 50%, 100% or
>> 200%.
>>
> 
> Thanks for the general advice but I think this is a bug. Don't you agree?
> 
> Now, whose bug is this?
> 

Well, you've convinced me that it's an intriguing problem :-)

Ok, off my head I see several possibilities:

* double scaling as I said before. Different rasterizes use different
algorithms to interpolate data when scaling bitmaps. It could be that
Acrobat does a better job at that than your printer driver (ghostscript?).

* genuine bug in the printer driver

* problems with jpg compression

I'd say it's well worth to investigate this, even if all what comes out is a
new warning for Scribus's preflighter.

/Andreas
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