KEY POINTS
  • Facial recognition technology requires hundreds of thousands of images to "learn" how to differentiate facial features.
  • NBC News obtained an IBM data set used to "train" the technology to learn faces. The set included millions of photos scraped by photo-hosting site Flickr, many without the consent of the subjects.
  • Legal experts and civil rights advocates claim using photos without consent especially endangers minorities, who could be profiled and targeted, since the technology could eventually be used for surveillance purposes.

Facial recognition can log you into your iPhone, track criminals through crowds and identify loyal customers in stores.

The technology — which is imperfect but improving rapidly — is based on algorithms that learn how to recognize human faces and the hundreds of ways in which each one is unique.