Getting pixel intensity vs. time for reading a Crookes radiometer

measureIntensities.py

import cv2

def measureIntensities(videoFileName, pointOfInterest):
    """
    Find the intensity of a point of interest for each frame
    """
    video = cv2.VideoCapture(videoFileName)
    intensities = []
    while video.isOpened():
        _returnCode, frame = video.read()
        if frame is None:
            break
        pixelValues = frame[pointOfInterest]
        intensities.append(pixelValues.sum())
    video.release()
    return intensities