Less than Full Face Recognition

Our own experiments consistently showed less than 100% for full face data, so is this data or context (lighting) dependent?

Researchers achieve 100 percent recognition rates for half and three-quarter faces  by University of Bradford

Facial recognition technology works even when only half a face is visible, researchers from the University of Bradford have found.

Using artificial intelligence techniques, the team achieved 100 per cent recognition rates for both three-quarter and half faces. The study, published in Future Generation Computer Systems, is the first to use machine learning to test the recognition rates for different parts of the face.  ... "