The effect of the distance from the webcam in heart rate estimation from face video images

Human facial video captured with a webcam can be processed to extract the heart rate. The objective of this paper is to show that the distance of the person from the webcam is an important parameter in the accuracy of the estimated heart rate. In fact, with increasing this distance, facial region is limited and the resolution of the video image is diminished which eventually leads to decrease in the accuracy of the estimated heart rate. We have carried out experiments on a data set of 12 subjects. The results of experiment have been compared with the heart rates recorded by a fingertip pulse oximeter in a statistical analysis framework. Our comparison reveals that the root mean square error of the difference of the recorded and the estimated heart rates has been increased from 8.91 for one-half meter away from the webcam to 16.77 for three meters away from the webcam.