1. Reading files from a folder

import os
import cv2
rootdir = "directory path"
for subdir, dirs, files in os.walk(rootdir):
    for file in files:
        frame = cv2.imread(os.path.join(subdir, file)) 

2. Installing opencv in pip

pip uninstall opencv-python-headless -y 
pip install opencv-python --upgrade

3. Printing an image

while(True):
    cv2.imshow('im', seg_img)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        cv2.destroyAllWindows()
        break