Video-based noncontact heart rate measurement using ear features

Heart rate measurement, especially out of clinical environments, has recently become a hot issue in the field of health monitoring. Video-based heart rate measurement is contactless and unobtrusive. However, most video-based heart rate measurements are sensitive to illumination changes. Inspired by a previous study which measures heart rate according to ballistocardiographic motion sensed by an ear-worn tri-axial accelerometer, we proposes to detect the ballistocardiographic motion of ear by tracking ear features in a video. Then we provide a video-based noncontact heart rate monitoring method. Scale-invariant features are employed to describe the structural characteristics of the ear, invariant to illumination changes and partial occlusion, which helps achieve movements of the ear. Relying on the signals of movements of ear features, underlying ballistocardiographic motion signal is separated and spectrum analyzed to estimate the heart rate. Experimental results demonstrate that by monitoring videos our method can obtain accurate heart rates close to the measurements gained by a contact sensor.