Which type of scan measures a person's external features through a digital video camera?

An iris scan captures the unique patterns of the colored ring of the eye using near-infrared light at close range, not external facial features through a standard video camera.

A retinal scan illuminates and maps the blood vessel patterns at the back of the eye using infrared light, requiring the subject to look into a specialized device.

Facial recognition scans use a digital video camera to capture the geometric spatial relationships between external facial features such as the distance between eyes, nose width, and jawline shape. It is entirely passive and non-contact, relying solely on visible-light imaging of the face's surface, which directly matches the description of measuring external features through a digital video camera.

Signature kinetics (also called dynamic signature verification) measures behavioral biometrics such as pen pressure, speed, and stroke order during signing, not physical features captured by a camera.