Video system detects pulse from tiny head movements

[Nipuna]

Video: Invisible head movements reveal your pulse

A video of your face can now accurately reveal your pulse. A new system, developed by Guha Balakrishnan and colleagues at the Massachusetts Institute of Technology, measures heart rate by analysing tiny head movements caused by blood flow to the head, which are invisible to the naked eye.

Using face recognition, it identifies a face and then typically selects hundreds of random points close to the person's mouth and nose. Movement is then tracked frame by frame, before filtering out frequencies that fall outside the range of a heartbeat to eliminate movement caused by breathing and changes in posture.

Tests revealed that pulse measurements were consistent with those produced by electrocardiograms, varying by just a few beats per minute. The technique was also able to estimate time intervals between beats, which can help determine if a person is at risk of heart problems.

Using video should be a useful alternative when monitoring babies and the elderly, where attaching cables can damage sensitive skin. Although slightly less accurate, the system can even provide a measurement when a face is not visible. "We've obtained a pulse from a sleeping newborn, from the back of a person's head and even from a person wearing a mask," the team reports.