Detecting Pulse From Head Motions in Video

Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory have developed a new algorithm that can accurately measure the heart rates of people depicted in ordinary digital video by analyzing imperceptibly small head movements that accompany the rush of blood caused by the heart’s contractions.

The researchers extract heart rate and beat lengths from videos by measuring subtle head motion caused by the Newtonian reaction to the influx of blood at each beat. The method tracks features on the head and performs principal component analysis (PCA) to decompose their trajectories into a set of component motions. It then chooses the component that best corresponds to heartbeats based on its temporal frequency spectrum.

Finally, the researchers analyze the motion projected to this component and identify peaks of the trajectories, which correspond to heartbeats. When evaluated on 18 subjects, the approach reported heart rates nearly identical to an electrocardiogram device. Additionally, the researchers were able to capture clinically relevant information about heart rate variability.

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Courtesy of Guha Balakrishnan, Fredo Durand and John Guttag