Reduce the File Size of PDF Documents with Preview on OS X

The PDF file format is ubiquitous for good reason, mostly because it allows for perfect preservation of a documents formatting, text, and other elements. However, sometimes PDF can be quite bloated and a file that should be not more than 200KB can suddenly be 1.5MB for no obvious reason. Adobe’s Acrobat X has functions to reduce/optimise the size of a pdf. On OSX you can achieve the same with Preview.

For PDF files that have not been optimized yet, the Preview app in OS X can often reduce the file size considerably by passing it through an export filter.

While it works great for text heavy files, it’s not a perfect solution for image-heavy slides. The “Reduce File Size” Quartz filter will indeed drastically shrink the file size of a pdf but the great savings in size come at a price. It will also make the slides look thoroughly awful. This is because the filter achieves its file size reduction by scaling all the images down by at least 50% and to no more than 512 pixels on a side, plus it uses aggressive JPEG compression. So not only will the images suffer from compression artifacts, they will also tend to get that lovely up-scaling blur.

Fortunatenly, anyone can create their own Quartz Filter with the ColorSync Utility shipped with OSX. The following zip file: PDF compression filters contains various files that reduce the file size while trying to minimise the amount of artifcats introduced in the images. It’s nowhere near as aggressive as the default Quartz-Filter.

The ColorSync Utility will by default save your own Quartz Filters in the following directory: /Users/YourName/Library/Filters/.

In order for the Filters to appear in the Save AS/Export menu the *.qfilter files need to be moved into the following directory

/Library/PDF Services/ Notice not in home folder (~/) but system-wide.

Afterwards the filters will appear in the dropdown menu of the export function:
Screenshot 2014-11-28 13.43.34

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