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OpenCV with Python By Example by Prateek Joshi

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Detecting and tracking faces

OpenCV provides a nice face detection framework. We just need to load the cascade file and use it to detect the faces in an image. Let's see how to do it:

import cv2 import numpy as np face_cascade = cv2.CascadeClassifier('./cascade_files/haarcascade_frontalface_alt.xml') cap = cv2.VideoCapture(0) scaling_factor = 0.5 while True: ret, frame = cap.read() frame = cv2.resize(frame, None, fx=scaling_factor, fy=scaling_factor, interpolation=cv2.INTER_AREA) gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) face_rects = face_cascade.detectMultiScale(gray, 1.3, 5) for (x,y,w,h) in face_rects: cv2.rectangle(frame, (x,y), (x+w,y+h), (0,255,0), 3) cv2.imshow('Face Detector', frame) c = cv2.waitKey(1) if c == 27: break cap.release() ...

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