The cyclical movement of blood from the heart to the head via the abdominal aorta and the carotid arteries causes the head to move in a periodic motion. The Inventors’ algorithm detects pulse from this movement. This method takes an input video of a person’s head and returns a pulse rate as well as a series of beat locations which can be used for the analysis of beat-to-beat variability. The motion of the head is extracted using feature tracking, upon which the motion corresponding to the pulse is isolated and projected onto a 1D signal to extract individual beat boundaries from the peaks of the trajectory. For this, principal component analysis (PCA) is used and the component whose temporal power spectrum best matches a pulse is selected.
The algorithm projects the trajectories of feature points onto this component and extracts the beat locations as local extrema. The correct source for analyzing and computing the duration of individual beats is chosen by examining the frequency spectra and selecting the source with the clearest main frequency. Average pulse rate is identified using this frequency. For more fine-grained analysis and calculation of beat durations, peak detections are performed in the time domain.