cv2 face recognition
How can you do face detection in Opencv? What is the best face detection algorithm?

Facial recognition and biometric scanning systems also use computer vision technology to identify individuals for security purposes. The most common example of computer vision in facial recognition is for securing smartphones. More advanced uses of facial recognition and biometrics include in residential or business security systems that use unique physiological features of individuals to verify their identity. Deep learning algorithms can identify the unique patterns in a person’s fingerprints and use it to control access to high-security areas such as high-confidentiality workplaces, such as nuclear powerplants, research labs, and bank vaults.

Update 11/13/19: the Newtek NDI app doesn't appear to be on the Play store anymore
Face detection using Haar cascades is a machine learning based approach where a cascade