Motion artifact reduction in PPG signals from face: Face tracking & stochastic state space modeling approach

The Photoplethymography(PPG) is generally measured on a finger or an ear using contact sensors. The recent several studies using non-contact sensor such as CCD camera and web-cam to measure PPG have been introduced. However the motion artifact issue is also emerging in non-contact camera sensing similar to contact-type one because it is sensitive to artifacts generated by subject´s head and body motion. In this paper, the two sequential approaches for a motion artifact reduction algorithm are presented; the one is a face tracking method that detects and tracks the skin region of face which is containing PPG signals, the other is the reduction method of motion artifact due to various head & face movement such as roll, yaw, pitch, translation and scale. Results of the proposed KF are compared to these of the FIR band pass filter(BPF).