Dieter Brehm

Remove tracking EXIF from your photos

While backing up some photos from Instagram to my computer (and to this blog), I happened to take a peek at the EXIF (Exchangable Image File Format) meta data while checking the image sizes. Oddly enough, there was a string of encoded "instructions."

metadata of jpeg from instagram, with hex encoded instructions The EXIF metadata in question, featuring an odd instruction set

After looking around on the net, some research has happened regarding these instruction sets. Although they may contain other information too, they certainly provide a tracking ID that Facebook can use to identify the photograph if it's found elsewhere on the internet (presumably, using its own internet crawlers).

Putting aside how scary that is for the moment, my main question was:

How can I strip all of this questionable metadata, on a Macbook, for many images?

Well, luckily there is ExifTool (opens new window), written by Phil Harvey. This tool is available on Homebrew, and can quickly batch process images in a folder! 😃

To strip all of the metadata from a photograph (Facebook already removes all the useful ones), we only need to run:

exiftool -all= photo.jpg

to strip the metadata while making a copy of the original with metadata preserved. This is a nicely written unix-style command line app, so it behaves ok with pipes, matching, etc. It's possible to pass *.jpg to process all photographs in the current directory.

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