我在一个黑色的窗口上画出人体坐标点，但是那个地方即使没有人体，坐标点也会保留下来，如何让这些点正常消失，这是代码。

import cv2
import numpy as np
import mediapipe as mp
# Create a VideoCapture object and read from input file
# If the input is the camera, pass 0 instead of the video file name
cap = cv2.VideoCapture('show.mp4')
height,width=480,852
blank_image = np.zeros((height,width,3), np.uint8)

mp_drawing = mp.solutions.drawing_utils
mp_pose = mp.solutions.pose
with mp_pose.Pose(min_detection_confidence=0.5, min_tracking_confidence=0.5) as pose:
    while (cap.isOpened()):

        ret, frame = cap.read()
        if ret :
            image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            image.flags.writeable = False
            results=pose.process(image)
            image = cv2.cvtColor(image, cv2.COLOR_RGB2BGR)
            mp_drawing.draw_landmarks(blank_image, results.pose_landmarks, mp_pose.POSE_CONNECTIONS,
                                      mp_drawing.DrawingSpec(color=(245, 117, 66), thickness=2, circle_radius=2),
                                      mp_drawing.DrawingSpec(color=(245, 66, 230), thickness=2, circle_radius=2)
                                      )
            cv2.imshow("",image)
            cv2.imshow(" ",blank_image)
            if cv2.waitKey(25) & 0xFF == ord('q'):
                break

        # Break the loop
        else:
            break

# When everything done, release the video capture object
cap.release()

# Closes all the frames
cv2.destroyAllWindows()

这就是

当我在身体上画点时，点消失了，但在黑色图像上没有。