Detecting faces in an image with OpenCV

OpenCV (Open Computer Vision) is an open source C++ library for computer vision. It features algorithms for image segmentation, object recognition, augmented reality, face detection, and other computer vision tasks.

In this recipe, we will use OpenCV in Python to detect faces in a picture.

Getting ready

You need OpenCV and the Python wrapper. You can install them with the following command:

conda install -c conda-forge opencv

How to do it...

1. First, we import the packages:

   >>> import io
       import zipfile
       import requests
       import numpy as np
       import cv2
       import matplotlib.pyplot as plt
       %matplotlib inline

2. We download and extract the dataset in the data/ subfolder:

   >>> url = ('https://github.com/ipython-books/'
              'cookbook-2nd-data/blob/master/'
              'family.zip?raw=true')
       r = io.BytesIO(requests.get(url).content)
       zipfile.ZipFile(r).extractall('data')

3. We open the JPG image with OpenCV:

   >>> img...