Once the data components were in place, I set about creating a graphical user interface to display the signals from the webcam pulse-reading algorithm and the finger sensor along with the heart rate and hrv from both. I opted to use Python for the excellent data visualization capabilities and because the Python community embraces open-source development and information sharing. Keeping my code open for others to use is important to me, personally. The GUI consists of an area where the video image of the subject along with the user-draggable and user-resizable region of interest, or roi, can be seen; an area where the real-time signal from the webcam and the real-time heart rate, hr, can be seen; and an area where the real-time signal and heart rate from the pulse sensor can be seen.