video-slicer.py

import cv2  # opencv.org
import numpy as np


def get_frame_averages(video_path):
    vc = cv2.VideoCapture(video)

    if vc.isOpened():
        rval, frame = vc.read()
    else:
        rval = False

    frames = []

    while rval:
        rval, frame = vc.read()
        av = np.average(frame, axis=1)
        frames.append(av)

    vc.release()

    return np.array(frames)


def squish_averages(averages, n):
    new_image = []
    frame_per_bucket = len(averages) / width or 1
    for frames in np.split(averages, range(frame_per_bucket, len(averages), frame_per_bucket)):
        av = np.average(frames, axis=0)
        new_image.append(av)
    return np.array(new_image)

video = 'test.mp4' # input video file path
imagePath = 'test.png' # output image path
width = 1920 # width of resulting image

frames = get_frame_averages(video)
image = squish_averages(frames, width)
cv2.imwrite(imagePath, image.transpose((1, 0, 2)))