PDF file size increases significantly when imported. Why?

Asked by Dave Hein on 2016-05-04

I've just noticed that all the PDF files I add to Calibre get increased in size. The most extreme was a 23MB PDF that got expanded to over 500MB!

I suspect that Calibre is turning off the compression within the PDFs.

Is there any way to prevent this "expansion" behavior?

Is there any way to make my PDFs small again?

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Dave Hein
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actionparsnip (andrew-woodhead666) said :
#1

What is the output of:

lsb_release -a; uname -a; apt-cache policy calibre

Thanks

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Dave Hein (dhein-8) said :
#2

I'm running this on OS X 10.9.5, not Linux.

Using Calibre 2.56.

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Manfred Hampl (m-hampl) said :
#3
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Dave Hein (dhein-8) said :
#4

Neither of those links addressed my issue.

I am simply adding a PDF to Calibre -- I am not a) converting a PDF to something else, and I am not b) converting something else to a PDF.

All I'm doing is adding a PDF (produced by the book publisher) to Calibre so that I can use Calibre to organize my e-books.

What is happening is that the original PDF (produced by the book publisher) is not preserved when I add it to Calibre ... instead Calibre seems to do some processing on it and creates a new file that appears to have all the native PDF compression removed (my assumption since the PDF stored by Calibre is about 20-50 times larger than the file I added).

I add new PDF ebooks to Calibre by dragging and dropping the files onto the Calibre main window.

My expectation would be that Calibre would do no conversion on those files.

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Dave Hein (dhein-8) said :
#5

I figured it out.

A standard Calibre install will not do this. The problem is caused by a plugin I had installed, DeDRM 6.0.8. That plugin apparently goes and rebuilds the PDF even if there is no DRM to strip out; the rebuilt PDF is not compressed.

I've disabled that plugin (don't need it on most things) and the problem has gone away.

Now I just have to redownload all those PDFs I've added over the last couple years ... so that I can recover all that disk space.

:-(

Or maybe there is a PDF processing utility that will recompress the PDFs.

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actionparsnip (andrew-woodhead666) said :
#6

OS X isn't supported here either. In future please use a Mac forum.

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Dave Hein (dhein-8) said :
#7

With respect to the "no OS X here, so go somewhere else" comment, the maker of Calibre has designated this forum as the place to ask questions about Calibre -- regardless of platform.

See https://answers.launchpad.net/calibre where it says "calibre questions are tracked in: calibre in Ubuntu".

That's why you will occasionally see questions from OS X users here.