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.. _cascade_classifier: |
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Cascade Classifier |
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******************* |
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Goal |
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===== |
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In this tutorial you will learn how to: |
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.. container:: enumeratevisibleitemswithsquare |
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* Use the :cascade_classifier:`CascadeClassifier <>` class to detect objects in a video stream. Particularly, we will use the functions: |
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* :cascade_classifier_load:`load <>` to load a .xml classifier file. It can be either a Haar or a LBP classifer |
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* :cascade_classifier_detect_multiscale:`detectMultiScale <>` to perform the detection. |
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Theory |
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====== |
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Code |
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==== |
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This tutorial code's is shown lines below. You can also download it from `here <https://code.ros.org/svn/opencv/trunk/opencv/samples/cpp/tutorial_code/objectDetection/objectDetection.cpp>`_ . The second version (using LBP for face detection) can be found `here <https://code.ros.org/svn/opencv/trunk/opencv/samples/cpp/tutorial_code/objectDetection/objectDetection2.cpp>`_ |
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.. code-block:: cpp |
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#include "opencv2/objdetect/objdetect.hpp" |
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#include "opencv2/highgui/highgui.hpp" |
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#include "opencv2/imgproc/imgproc.hpp" |
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#include <iostream> |
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#include <stdio.h> |
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using namespace std; |
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using namespace cv; |
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/** Function Headers */ |
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void detectAndDisplay( Mat frame ); |
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/** Global variables */ |
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String face_cascade_name = "haarcascade_frontalface_alt.xml"; |
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String eyes_cascade_name = "haarcascade_eye_tree_eyeglasses.xml"; |
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CascadeClassifier face_cascade; |
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CascadeClassifier eyes_cascade; |
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string window_name = "Capture - Face detection"; |
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RNG rng(12345); |
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/** @function main */ |
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int main( int argc, const char** argv ) |
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{ |
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CvCapture* capture; |
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Mat frame; |
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//-- 1. Load the cascades |
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if( !face_cascade.load( face_cascade_name ) ){ printf("--(!)Error loading\n"); return -1; }; |
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if( !eyes_cascade.load( eyes_cascade_name ) ){ printf("--(!)Error loading\n"); return -1; }; |
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//-- 2. Read the video stream |
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capture = cvCaptureFromCAM( -1 ); |
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if( capture ) |
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{ |
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while( true ) |
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{ |
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frame = cvQueryFrame( capture ); |
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//-- 3. Apply the classifier to the frame |
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if( !frame.empty() ) |
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{ detectAndDisplay( frame ); } |
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else |
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{ printf(" --(!) No captured frame -- Break!"); break; } |
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int c = waitKey(10); |
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if( (char)c == 'c' ) { break; } |
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} |
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} |
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return 0; |
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} |
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/** @function detectAndDisplay */ |
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void detectAndDisplay( Mat frame ) |
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{ |
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std::vector<Rect> faces; |
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Mat frame_gray; |
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cvtColor( frame, frame_gray, CV_BGR2GRAY ); |
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equalizeHist( frame_gray, frame_gray ); |
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//-- Detect faces |
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face_cascade.detectMultiScale( frame_gray, faces, 1.1, 2, 0|CV_HAAR_SCALE_IMAGE, Size(30, 30) ); |
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for( int i = 0; i < faces.size(); i++ ) |
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{ |
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Point center( faces[i].x + faces[i].width*0.5, faces[i].y + faces[i].height*0.5 ); |
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ellipse( frame, center, Size( faces[i].width*0.5, faces[i].height*0.5), 0, 0, 360, Scalar( 255, 0, 255 ), 4, 8, 0 ); |
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Mat faceROI = frame_gray( faces[i] ); |
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std::vector<Rect> eyes; |
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//-- In each face, detect eyes |
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eyes_cascade.detectMultiScale( faceROI, eyes, 1.1, 2, 0 |CV_HAAR_SCALE_IMAGE, Size(30, 30) ); |
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for( int j = 0; j < eyes.size(); j++ ) |
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{ |
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Point center( faces[i].x + eyes[j].x + eyes[j].width*0.5, faces[i].y + eyes[j].y + eyes[j].height*0.5 ); |
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int radius = cvRound( (eyes[j].width + eyes[i].height)*0.25 ); |
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circle( frame, center, radius, Scalar( 255, 0, 0 ), 4, 8, 0 ); |
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} |
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} |
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//-- Show what you got |
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imshow( window_name, frame ); |
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} |
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Explanation |
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============ |
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Result |
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====== |
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#. Here it is: |
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========== ========== |
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|CCH| |CCLBP| |
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========== ========== |
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.. |CCH| image:: images/Cascade_Classifier_Tutorial_Result_Haar.jpg |
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:align: middle |
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:height: 200pt |
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.. |CCLBP| image:: images/Cascade_Classifier_Tutorial_Result_LBP.jpg |
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:align: middle |
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:height: 200pt |
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After Width: | Height: | Size: 55 KiB |
After Width: | Height: | Size: 52 KiB |
After Width: | Height: | Size: 39 KiB |
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