Even on Boing Boing, it clearly states that meta data are generated on the users’ devices:
When someone uses Pixek to take a photo, the software performs machine learning analysis on their device to recognize objects and elements of photos, then adds tags to the image for each one. It then encrypts the image along with its tags, using a unique key stored only the user’s phone.
According to this, Pixek allows encrypted meta-data to be searched on the server, so you don’t even need the complete meta-data DB on the device.
