[Libreoffice-bugs] [Bug 121866] New: pdf export creates file that doesn't print graphics correctly

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=121866

            Bug ID: 121866
           Summary: pdf export creates file that doesn't print graphics
                    correctly
           Product: LibreOffice
           Version: 4.3.3.2 release
          Hardware: All
                OS: Linux (All)
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Impress
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: tkortht at gmail.com

I'm using LibreCad to make the drawing, exporting it as a graphic, importing
that graphic into Impress, adding text etc, and then exporting that as a pdf. 
The resulting file looks great but when it's printed only the text prints well.
 The drawings are horrid. I've tried printing the file from linux, pc, and mac
to different printers and nothing helped so it's something inside the file.

I went online and found lots of complaints about this but none of the proffered
solutions worked.  Print as image makes it worse. I use to work for HP's
printer division and chasing down print defects like this is what I used to do
so I think I know what's going on.  I can't explain how I knew this would work,
but I started testing outputting the cad file as different graphics format at
various resolutions and finally got it to work by exporting from LibreCad as a
png with a rez less than 150 and then using the lossless compression option
when exporting the Impress file to pdf. Only low rez works, Jpegs don't work,
Tif's don't work, svg's sorta work.  EPS works but the file is much larger so I
stuck with the png solution.

You don't have to print to test this, print preview from the pdf reader will
show this.

I no longer have the tools to delve very deep so I can only guess that there's
something in the compression algorithm that your code is using for processing
the image file that is reacting to the fine line hash marks in the cad
drawings. That compression algorithm doesn't deal well with all of the parallel
lines so it creates something like a moire pattern when it comes time to
translate the file into raster data for printing.  Changing image type changes
how the compression is done and the lower rez image decreases the frequency of
the interference pattern.

hope that helps, thanks for the good work.

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