[Libreoffice-bugs] [Bug 108032] New: PNGs are expanded 20 times on export (w/lossless!), leading to bloated PDFs.

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=108032

            Bug ID: 108032
           Summary: PNGs are expanded 20 times on export (w/lossless!),
                    leading to bloated PDFs.
           Product: LibreOffice
           Version: 5.1.4.2 release
          Hardware: All
                OS: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Printing and PDF export
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: presentmeaninvite at gmail.com

Today I’ve made a document, it’s resulting size was quite normal:

$ ls -s *odt 
5.9M Руководство по системе управления порталом.odt

All images are linked and reside under ‘img’ subfolder, which doesn’t take more
than the document itself.

$ du -hs img/
2.1M    img/

And the resulting document takes… whooping 53 MiB(!).

$ ls -s Руководство\ по\ системе\ управления\ порталом.pdf 
53M Руководство по системе управления порталом.pdf

It was exported with PDF/A-a1 option, and I understand, that there are also
fonts embedded into the doc, but that’s around 5 megabytes including all the
variants (bold/italic), not more. Let’s export one image from a PDF viewer to
disk and compare the size:

$ du -hb '/home/dtr/work/docs/website cms/platformiosedit.png'
1836974 /home/dtr/work/docs/alma tv/website cms/platformiosedit.png

$ du -hb '/home/dtr/work/docs/website cms/img/0250.png'
87942   /home/dtr/work/docs/website cms/img/0250.png

What?.. 

$ echo 'scale=1; 1836974/87942' | bc -q
20.8

Twenty, almost twenty one times bigger? What kind of archiving is that?
Let’s not use PDF/A-a1 and compare again

$ ls -s 'Руководство по системе управления порталом w\o PDF\A-a1.pdf'
2.0M Руководство по системе управления порталом w\o PDF\A-a1.pdf

Two megabytes! Two! As it should be. It is interesting to export that same
iamge from the PDF viewer again.

$ du -hb 'platfromiosedit2.png'
91046   platfromiosedit2.png

Well, the size is bigger than that of the original image, but at least it’s
close.

My question stays the same since #93462: why LibreOffice thinks, that it should
modify original images, when it was clearly said to use Lossless images?

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