Figure 3.

The flowchart of our proposed data processing procedure which consists of acquiring screenshot during the measurement, cropping acquired images, converting RGB image to HSV color space, obtaining a binary image after denoising background from HSV images, and scaling a binary image to values in x-y axis. The heart rate is extracted from peak-to-peak (or pulse) interval from the constructed PPG signal (left). The acquired smartphone PPG signal is compared to gold-standard PPG signal acquired by NeXus-10 MKII (right).