How do I display all images missing a given piece of metadata in Apple Aperture?

Question

I'm slowly working on cleaning up the metadata in all my old images that I imported into Aperture from iPhoto. I'd like to get a list of the images that I haven't added a certain metadata field to but I can't figure out how to search for a missing value.

For example I'd like to get a list of all images that don't have a GPS location, or all images that don't have copyright info, etc.

Answer

Open up any metadata search criteria, add in either EXIF or IPTC fields you want to search by (using the "Add Rule" dropdown), and indicate you want images where the EXIF/IPTC "is empty".

An example for copyright:

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