Investigation of Five Algorithms for Selection of the Optimal Region of Interest in Smartphone Photoplethysmography

Figure 2

A video frame illustrating the positions of the optimal regions of interest (ROI) selected by the five algorithms. A, B, C, and D indicate the optimal ROI selected by the VAR, SER, TM, and TD algorithm, respectively. Note that C is also the optimal ROI selected by the GRAD algorithm.