Contactless Heart Rate Measurement System Based RGB Camera, Cascade Object Detector and Independent Component Analysis

Abstract

This paper focuses on the development of non-contact heart rate measurement based on video analysis. This project implements an RGB camera (OV2640 with ESP32 Cam) and an FTDI Programmer which enables the sensor to record videos from a subject at a distance of 20 cm. The Region of Interest (ROI) of the facial skin tissue was detected by using Cascade Object Detector (COD) which can detect object categories whose aspect ratio does not vary significantly. Then, the Independent Component Analysis (ICA) was applied by extracting distinct source signals (red, blue and green channels) from the observed mixed colour signals. Next, the average pixel of ROI was calculated based on red, green and blue facial pixel at given time. Finally, the heart rate was extracted from the frequency spectrum of the average pixel. The performance of the developed contactless system was compared with the fingertip pulse oximeter (Oxitech) by means of percentage of error (PE). The lowest range of PE is between 0 to 5.62 % whereas the highest PE is 22.54 %. The highest error was due to incorrectly captured ROI of facial skin area as well as due to the movement made during the recording session. Meanwhile, the average time for the developed system to process the heart rate of the subject is 4.51 minutes. In future, a robust ROI algorithm can be adopted to reduce error contributed by incorrectly ROI selection. Other than that, this project has a potential to contribute to the area of contactless measurement of oxygen saturation.