Real-time Heart Rate Measuring System Based On Webcam

Heart rate is one of the fundamental human parameters. Changes of physical condition can be detected and some unexpected situation can be avoided by monitoring it which is also significant for preventing and controlling cardiovascular disease. Professional and complex sensors are needed by traditional heart rate monitors generally which are expensive and uncomfortable because of direct contact to the human skin.In our system, professional hardware devices were replaced by a widely used personal computer equipped with a webcam. Image processing and signal processing were performed to measure heart rate without direct contact with skin. It is low-cost, practicable and easy to operate which will provide great promise for home healthcare’s popularization and will benefit double-blind experiments’ standardization in biomedical research.These following contents were included in this paper:1. Existing heart rate measuring method and devices were studied.2. Principle and application of PPG were summarized. Especially a new PPG technique image PPG was introduced.3. A heart rate measuring method based on image PPG was proposed. Firstly, a face image sequence was shot by the webcam without contact with human body. Followly we used digital image processing to extract the facial color change signal from which pulse wave was extracted then and heart rate was calculated by peak detection algorithm.4. Experiments were conducted to verify eye blinking’s interference to pulse wave. To eliminate this interference, we proposed an ROI extraction method utilizing statistical face detection algorithm and eyes detection algorithm based on gray-level integration projection.5. Pulse wave extraction method was studied to achieve efficiency and stability by reasonable color channel selection.6. Signal denoising method was studied including wavelet denoising, threshold quantization, decomposition level and wavelet function selection.7. Ambient brightness and webcam parameters like frame rate and image resolution were researched by experiments to achieve the highest accuracy by adjusting them.8. The real-time heart rate measuring system with human-computer interaction interface under Windows operating system was realized. Heart rate and its variation wave were shown on the screen in real-time.9. Experiments were conducted to determine the measuring accuracy.