"""
Face detection using haar feature-based cascade classifiers
"""
# Import required packages:
import cv2
import numpy as np
from matplotlib import pyplot as plt
def show_img_with_matplotlib(color_img, title, pos):
"""Shows an image using matplotlib capabilities"""
img_RGB = color_img[:, :, ::-1]
ax = plt.subplot(2, 2, pos)
plt.imshow(img_RGB)
plt.title(title)
plt.axis('off')
def show_detection(image, faces):
"""Draws a rectangle over each detected face"""
for (x, y, w, h) in faces:
cv2.rectangle(image, (x, y), (x + w, y + h), (255, 0, 0), 5)
return image
# Load image and convert to grayscale:
img = cv2.imread("test_face_detection.jpg")
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
# Load cascade classifiers:
cas_alt2 = cv2.CascadeClassifier("haarcascade_frontalface_alt2.xml")
cas_default = cv2.CascadeClassifier("haarcascade_frontalface_default.xml")
# Detect faces:
faces_alt2 = cas_alt2.detectMultiScale(gray)
faces_default = cas_default.detectMultiScale(gray)
print(cv2.face.getFacesHAAR(img, "haarcascade_frontalface_alt2.xml"))
retval, faces_haar_alt2 = cv2.face.getFacesHAAR(img, "haarcascade_frontalface_alt2.xml")
faces_haar_alt2 = np.squeeze(faces_haar_alt2)
retval, faces_haar_default = cv2.face.getFacesHAAR(img, "haarcascade_frontalface_default.xml")
faces_haar_default = np.squeeze(faces_haar_default)
# Draw face detections:
img_faces_alt2 = show_detection(img.copy(), faces_alt2)
img_faces_default = show_detection(img.copy(), faces_default)
img_faces_haar_alt2 = show_detection(img.copy(), faces_haar_alt2)
img_faces_haar_default = show_detection(img.copy(), faces_haar_default)
# Create the dimensions of the figure and set title:
fig = plt.figure(figsize=(10, 8))
plt.suptitle("Face detection using haar feature-based cascade classifiers", fontsize=14, fontweight='bold')
fig.patch.set_facecolor('silver')
# Plot the images:
show_img_with_matplotlib(img_faces_alt2, "detectMultiScale(frontalface_alt2): " + str(len(faces_alt2)), 1)
show_img_with_matplotlib(img_faces_default, "detectMultiScale(frontalface_default): " + str(len(faces_default)), 2)
show_img_with_matplotlib(img_faces_haar_alt2, "getFacesHAAR(frontalface_alt2): " + str(len(faces_haar_alt2)), 3)
show_img_with_matplotlib(img_faces_haar_default, "getFacesHAAR(frontalface_default): " + str(len(faces_haar_default)),
4)
# Show the Figure:
plt.show()
