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I have a 35-page academic paper in foo.pdf created using LaTeX. The full document is 950 KB.

I want to extract the figures and tables at the end of document into a separate file, so I open the document in Preview and drag the pages I need onto the desktop. This creates a new file, foo (dragged).pdf which is 2.2 MB.

How can the last 10 pages of a 35-page document be 2.4 times larger than the original document? Is OSX adding lots of metadata to these pages? I consider this a curiosity more than a problem, but still...

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2 Answers

The Mac OS does not optimize PDF files the way Acrobat or other PDF generating applications usually do. It may also be that when you drag the page to the desktop is is making a PDF that is really just a wrapper for an bitmap image.

You could try using "Export As..." by right-clicking a thumbnail of a page and see if that results in smaller files. Another choice would be to delete all of the pages you do not want to keep and then save the file.

Here is a decent thread about optimizing PDF file sizes in Mac OS. https://discussions.apple.com/thread/3213814?start=0&tstart=0

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PDF files are text files with some binary fields in them, so you should be able to just open the two files in a text editor (or use more / vi / grep ) to inspect each. A file comparison tool might also help you discern whether Preview is re-encoding the assets in a sub-optimal manner.

Automator also has some PDF processing tools including compression, compression of images and rendering the pages as images. I would try exporting the resulting PDF from Preview and select the Quartz filter of "reduce file size" to see if perhaps that would reduce the size.

You can see several related questions where others have noticed this effect where the standard settings increase the size of some types of content.

As a postscript, a 35 page paper in ascii format weighing in at 950K is pretty efficient but also still an order of magnitude larger than some basic texts that are in the 60 page range even with illustrations on each page.

Take for example this book from Project Gutenberg - The Cat and the Mouse by Hartwell James and John R. Neill

  • The plain text (UTF-8) and HTML versions are in the 70 kB range
  • The ePub version is a sleek 45 kB with no images, but swells to 2.8 MB with images.

If I take the HTML version and inspect it in Safari, it's clear the 75 kB is just the main text/HTML file and not all the included images. Printing that page to PDF using Safari (which uses the same rendering engine as Preview) - I get a 3.7 MB file that can be compressed with Quartz reduce file size filter to 2.2 MB.

Hopefully these examples help you in deciding whether to generate all versions of your files in LaTeX or live with the libraries for PDF generation on OS X.

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