six colors

by Jason Snell & Dan Moren

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By Dan Moren

Quick Tip: Adding Preview filters in macOS Sierra

The other day, a friend was asking me about compressing PDFs without losing too much quality—in particular about a custom Quartz filter in Preview, which we’ve used over the years for that purpose. It’s based on this Macworld tip by Kirk McElhearn from 2012, and involves copying and altering the existing “Reduce File Size” Quartz filter to provide a better balance between compression and quality.

While most of that tip still works as described, there’s a bit of a wrinkle when it comes to macOS Sierra. The original tip specifies dropping the new file in /System/Library/Filters, but in Sierra, that folder is off-limits—even to administrators.1 You simply can’t drop a file in there.

That’s okay! Because there are actually three Library folders in a macOS installation2, and often if you can’t use one of them, another will do. In this case, the solution was to create a Filters directory in /Library (that’s the one at the root of your Mac) and put the file in there. Sure enough, the next time I went to export a file from Preview, my “Reduce File Size - Better” option appeared in the Quartz Filter dropdown.

Reduce File Size

(One puzzle I couldn’t solve, however, was that the PDF he was trying to compress actually ended up larger after running it through the filter. I double-checked myself and got the same result, even though the resolution did not appear to have changed. Bit of a head-scratcher there, though I expect it has something to do with the original already being optimally compressed by the program that created it.)

  1. Even resorting to sudo in command-line didn’t help me out.  ↩

  2. As of Sierra, my rubric for these is: ~/Library: Sure, whatever you want to put in here!; /Library/Filters: Okay, but this applies to every user on this machine.; /System/Library: As if it were a swarm of bees, you should stay away from this folder. ↩

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[Dan Moren is a tech writer, novelist, podcaster, and the Official Dan of Six Colors. You can email him at or find him on Twitter at @dmoren.]