OpenCV When face not detected in live feed, exit-CodePudding

So I am trying to make a code where when face is detected from webcam it shows a green square around face. That part is done. What I want to make next is that when face is no longer detected by program that it break the loop and exit program. I tried ways through "if" or "else" or find something online but I was not going anywhere. Is there some way to do it? Here is my code:

import cv2
import os
import time

cascPath = os.path.dirname(
    cv2.__file__)   "/data/haarcascade_frontalface_alt2.xml"
faceCascade = cv2.CascadeClassifier(cascPath)
video_capture = cv2.VideoCapture(0)
while True:
    ret, frame = video_capture.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    faces = faceCascade.detectMultiScale(gray,
                                         scaleFactor=1.1,
                                         minNeighbors=5,
                                         minSize=(60, 60),
                                         flags=cv2.CASCADE_SCALE_IMAGE)
    for (x,y,w,h) in faces:
        cv2.rectangle(frame, (x, y), (x   w, y   h),(0,255,0), 2)
    cv2.imshow('Video', frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
video_capture.release()
cv2.destroyAllWindows()

CodePudding user response：

How about adding this? Count the number of times no face is detected; break if passes a threshold:

iter_with_no_faces=0 #put this outside the main loop
### put the follwing after updating `faces`
if len(faces) ==0:
    iter_with_no_faces =1
##  add break condition as this:
if iter_with_no_faces >100:
    break

you can iter_with_no_faces in the faces loop: iter_with_no_faces=0

In sum, this might work with slight modification:

import cv2
import os
import time

cascPath = os.path.dirname(
    cv2.__file__)   "/data/haarcascade_frontalface_alt2.xml"
faceCascade = cv2.CascadeClassifier(cascPath)
video_capture = cv2.VideoCapture(0)
iter_with_no_faces=0 #put this outside the main loop
while True:
    ret, frame = video_capture.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    faces = faceCascade.detectMultiScale(gray,
                                         scaleFactor=1.1,
                                         minNeighbors=5,
                                         minSize=(60, 60),
                                         flags=cv2.CASCADE_SCALE_IMAGE)
    for (x,y,w,h) in faces:
        cv2.rectangle(frame, (x, y), (x   w, y   h),(0,255,0), 2)

    if len(faces) ==0:
        iter_with_no_faces =1
    else:
        iter_with_no_faces=0 # I assume you want to continue program when a face detected for a duration. you can omit else statement
    if iter_with_no_faces >100: #set this threshold to larger or smaller number
        break
    cv2.imshow('Video', frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
video_capture.release()
cv2.destroyAllWindows()

CodePudding user response：

import cv2


def main():
    cascPath = './haarcascade_frontalface_alt2.xml'  # path to the xml file - change to your path
    faceCascade = cv2.CascadeClassifier(cascPath)
    video_capture = cv2.VideoCapture(0)
    for i in range(10 ** 10):
        ret, frame = video_capture.read()
        if ret:
            gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
            faces = faceCascade.detectMultiScale(gray,
                                                 scaleFactor=1.1,
                                                 minNeighbors=5,
                                                 minSize=(60, 60),
                                                 flags=cv2.CASCADE_SCALE_IMAGE)
            if len(faces) > 0:
                for (x, y, w, h) in faces:
                    cv2.rectangle(frame, (x, y), (x   w, y   h), (0, 255, 0), 2)
                cv2.imshow('Video', frame)
                k = cv2.waitKey(1)
                if k == ord('q'):
                    break
            else:
                print('No face detected on iter {}'.format(i))
                # add here break or whatever you want to do if no face detected
    video_capture.release()
    cv2.destroyAllWindows()
    return


if __name__ == '__main__':
    main()