Using a scanner often results in large files. OS X preview program allows to export to multiple formats. Choosing filetype pdf enables the option to apply quartz filters (generic export dialog; shortcut export to pdf does not show quartz filters in OS X 10.11.6). The builtin quartz filter reduce file size does create tiny documents but text might get unreadable.

But the builtin tool ColorSync allows to modify and create quartz filters (german howto with screenshots here). If a newly created filter should show up in the export dialog of the preview program it has to be copied from
/Users/your_name/Library/Filters to /Library/PDF Services
(tested in OS X 10.11.6).

Example of settings for small but (rather) readable pdf files:

  • Image: pixel per inch = 100; quality = high; all other settings empty
  • Image (gray): pixel per inch = 100; quality = high; all other settings empty
  • Image compression: jpeg; quality = slider one tick below medium position

To shrink multiple pdf files the custom quartz filter can be used from the command line:

  • Open Tools / Automator and create a new workflow
  • add action pdf / apply quartz filter
  • do not add other actions
  • save this workflow, e.g. as /yourpath/pdfreduce
  • copy all pdf files which should be converted to a new folder
  • open a terminal and cd to the folder with pdf files which should be shrinked
  • to convert one file run: automator -i yourdoc.pdf /yourpath/pdfreduce.workflow
  • multiple files: for f in *.pdf; do echo “$f”; automator -i “$f” pdfreduce.workflow; done

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