Cardiorespiratory Parameters Monitoring Through a Single Digital Camera in Real Scenarios: ROI Tracking and Motion Influence

Monitoring of heart rate (HR) and respiratory rate (fR) is fundamental to assess the health status of an individual. To address this scope, technologies which frame the upper body and the face regions of a subject without any physical contact can be used. Motion artifacts can affect the applicability of non-contact methods to the continuous monitoring of these parameters as well as the computational burden. This paper focuses on a technique based on images captured with a single digital camera for the continuous estimation of HR andfR. The main goal is to analyze how velocity of face movements and ROI tracking duration influence the performance of the method. Tests were performed on healthy volunteers during motionless trials (i.e., at rest and after exercise), head and torso movements, and during physical exercise. Results demonstrated that a continuous estimation of HR andfRcan be performed with acceptable errors under changing ROI tracking duration and velocity in motionless trials (MAE below 5 bpm and 3.42 breaths∙min-1for HR andfR, respectively), whereas during movements (mimicking head and torso movements, and during exercise) the error increases (MAE up to 5.42 bpm and up to 5.03 breaths∙min-1for HR andfR, respectively). The proposed investigation can provide a framework for the continuous estimation of HR andfRduring both static and dynamic activities by optimizing the ROI tracking duration under different velocity of face movements.