opencv/doc/tutorials/objdetect/cascade_classifier/cascade_classifier.markdown

Cascade Classifier

Goal

In this tutorial you will learn how to:

• Use the @ref cv::CascadeClassifier class to detect objects in a video stream. Particularly, we will use the functions:
  • @ref cv::CascadeClassifier::load to load a .xml classifier file. It can be either a Haar or a LBP classifer
  • @ref cv::CascadeClassifier::detectMultiScale to perform the detection.

Theory

Code

@add_toggle_cpp This tutorial code's is shown lines below. You can also download it from here @include samples/cpp/tutorial_code/objectDetection/objectDetection.cpp @end_toggle

@add_toggle_java This tutorial code's is shown lines below. You can also download it from here @include samples/java/tutorial_code/objectDetection/cascade_classifier/ObjectDetectionDemo.java @end_toggle

@add_toggle_python This tutorial code's is shown lines below. You can also download it from here @include samples/python/tutorial_code/objectDetection/cascade_classifier/objectDetection.py @end_toggle

Explanation

Result

-# Here is the result of running the code above and using as input the video stream of a build-in webcam:

![](images/Cascade_Classifier_Tutorial_Result_Haar.jpg)

Be sure the program will find the path of files *haarcascade_frontalface_alt.xml* and
*haarcascade_eye_tree_eyeglasses.xml*. They are located in
*opencv/data/haarcascades*

-# This is the result of using the file lbpcascade_frontalface.xml (LBP trained) for the face detection. For the eyes we keep using the file used in the tutorial.

![](images/Cascade_Classifier_Tutorial_Result_LBP.jpg)

Additional Resources

-# Paul Viola and Michael J. Jones. Robust real-time face detection. International Journal of Computer Vision, 57(2):137–154, 2004. @cite Viola04 -# Rainer Lienhart and Jochen Maydt. An extended set of haar-like features for rapid object detection. In Image Processing. 2002. Proceedings. 2002 International Conference on, volume 1, pages I–900. IEEE, 2002. @cite Lienhart02 -# Video Lecture on Face Detection and Tracking -# An interesting interview regarding Face Detection by Adam Harvey -# OpenCV Face Detection: Visualized on Vimeo by Adam Harvey