Contactless iPPG Extraction Using Infrared Imaging

Image-based photoplethysmography (iPPG) represents a non-invasive and contactless optical technique extensively utilized for heart rate monitoring. In this methodology, the skin's surface is illuminated by a light source, and a photodetector measures volumetric variations in blood circulation. To circumvent the blinding effects associated with high-intensity visible light sources, this pilot study explores the feasibility of employing infrared (IR) light and a high-speed camera for contactless continuous pulse rate measurement. The IR light is directed onto the facial region, and a high-speed camera, capable of capturing video frames at high sampling rate, records the reflected light, enabling the extraction of iPPG signals from the acquired video frames. The efficacy of the developed algorithm was evaluated in ten experiments, encompassing both resting and exercising conditions. A wrist-worn pulse oximeter served as a reference for comparison. The article details the process of image extraction and signal processing implementation, presenting the outcomes of a signal processing pipeline. Furthermore, the detected pulse rates were compared with measurements obtained from the pulse oximeter.