1+ import cv2
2+ cap = cv2 .VideoCapture (0 )
3+ face_cascade = cv2 .CascadeClassifier ("haarcascade_frontalface_alt.xml" )
4+ 5+ while True :
6+ ## capture camera frame, and ret store true and false
7+ r , frame = cap .read ()
8+ gray_frame = cv2 .cvtColor (frame ,cv2 .COLOR_BGR2GRAY )
9+ 10+ if r == False :
11+ continue
12+ faces = face_cascade .detectMultiScale (gray_frame ,1.3 ,5 )
13+ 14+ ## """ The first argument is the image, the second is the
15+ ## scalefactor (how much the image size will be reduced at each image scale),
16+ ## and the third is the minNeighbors (how many neighbors each rectangle should have)"""
17+ 18+ for (x ,y ,w ,h ) in faces :
19+ cv2 .rectangle (frame ,(x ,y ),(x + w ,y + h ),(255 ,125 ,0 ),2 )## color and width
20+ cv2 .putText (frame ,"DETECTED" ,(x ,y - 10 ),cv2 .FONT_HERSHEY_SIMPLEX ,1 ,(100 ,125 ,255 ),1 ,cv2 .LINE_AA )
21+ cv2 .imshow ("video frame" ,frame )
22+ key_pressed = cv2 .waitKey (1 ) & 0xFF
23+ 24+ ## """cv2.waitKey() returns a 32 Bit integer value (might be dependent on the platform).
25+ ## The key input is in ASCII which is an 8 Bit integer value. So you only care
26+ ## about these 8 bits and want all other bits to be 0. This you can achieve with:0xFF"""
27+ 28+ ### ord converts characters in unicode
29+ if key_pressed == ord ('n' ):
30+ break
31+ 32+ cap .release ()
33+ cv2 .destroyAllWindows ()
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