Ubuntu中的opencv python屏幕截图

Question

我正在尝试捕获屏幕并使用opencv-python连续显示图像。但是由于某些原因，图像没有像通常那样堆叠在一起。请查看下面的源代码和屏幕截图。我正在使用Ubuntu 18.04。谢谢！！

    import time
    import cv2
    import mss
    import numpy as np

    with mss.mss() as sct:
        # Part of the screen to capture
        monitor = {"top": 40, "left": 0, "width": 800, "height": 640}

        while True:
            last_time = time.time()

            # Get raw pixels from the screen, save it to a Numpy array
            img = np.array(sct.grab(monitor))

            # Display the picture
            cv2.imshow('frame', img)

            print("fps: {}".format(1 / (time.time() - last_time)))

            # Press "q" to quit
            if cv2.waitKey(1) & 0xFF == ord("q"):
                cv2.destroyAllWindows()
                break