title: My computer does not recognize the import cv2 library
body: <p>The program should perform facial recognition using Open CV</p>
  <p>I already downloaded the library with <code>pip install opencv-python</code> and also tried with <code>pip install opencv-python-headless</code>.</p>
  <pre><code>import cv2
  
  face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
  
  cap = cv2.VideoCapture(0)
  
  while True:
      _, img = cap.read()
      gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
      faces = face_cascade.detectMultiScale(gray,1.1,4)
      for (x,y,w,h) in faces:
          cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
      cv2.imShow('img',img)
      k = cv2.waitKey(30)
      if k == 27: #27 = ascii ---(space)---
          break
  
  cap.release() #Stop
  </code></pre>