Fig. 3.

Flowchart of HRVCam: iPPG signals extracted from raw videos is divided into epochs. Step 1: iPPG signal passed through an adaptive bandpass filter that estimates the cut-off frequencies of the filter based on the noise structure in the iPPG signal. The bandpass filter filters out the fundamental harmonic signal. Step 2: Discrete energy separation algorithm was used to extract out the instantaneous frequency. Step 3: the instantaneous frequency is converted to interbeat intervals by reconstructing the FM signal.