94 lines
2.7 KiB
C++
94 lines
2.7 KiB
C++
/**
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* @function moments_demo.cpp
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* @brief Demo code to calculate moments
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* @author OpenCV team
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*/
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#include "opencv2/imgcodecs.hpp"
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#include "opencv2/highgui.hpp"
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#include "opencv2/imgproc.hpp"
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#include <iostream>
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using namespace cv;
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using namespace std;
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Mat src; Mat src_gray;
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int thresh = 100;
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int max_thresh = 255;
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RNG rng(12345);
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/// Function header
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void thresh_callback(int, void* );
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/**
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* @function main
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*/
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int main( int, char** argv )
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{
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/// Load source image and convert it to gray
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src = imread( argv[1], IMREAD_COLOR );
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/// Convert image to gray and blur it
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cvtColor( src, src_gray, COLOR_BGR2GRAY );
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blur( src_gray, src_gray, Size(3,3) );
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/// Create Window
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const char* source_window = "Source";
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namedWindow( source_window, WINDOW_AUTOSIZE );
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imshow( source_window, src );
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createTrackbar( " Canny thresh:", "Source", &thresh, max_thresh, thresh_callback );
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thresh_callback( 0, 0 );
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waitKey(0);
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return(0);
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}
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/**
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* @function thresh_callback
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*/
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void thresh_callback(int, void* )
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{
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Mat canny_output;
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vector<vector<Point> > contours;
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vector<Vec4i> hierarchy;
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/// Detect edges using canny
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Canny( src_gray, canny_output, thresh, thresh*2, 3 );
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/// Find contours
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findContours( canny_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) );
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/// Get the moments
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vector<Moments> mu(contours.size() );
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for( size_t i = 0; i < contours.size(); i++ )
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{ mu[i] = moments( contours[i], false ); }
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/// Get the mass centers:
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vector<Point2f> mc( contours.size() );
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for( size_t i = 0; i < contours.size(); i++ )
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{ mc[i] = Point2f( static_cast<float>(mu[i].m10/mu[i].m00) , static_cast<float>(mu[i].m01/mu[i].m00) ); }
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/// Draw contours
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Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
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for( size_t i = 0; i< contours.size(); i++ )
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{
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Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
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drawContours( drawing, contours, (int)i, color, 2, 8, hierarchy, 0, Point() );
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circle( drawing, mc[i], 4, color, -1, 8, 0 );
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}
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/// Show in a window
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namedWindow( "Contours", WINDOW_AUTOSIZE );
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imshow( "Contours", drawing );
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/// Calculate the area with the moments 00 and compare with the result of the OpenCV function
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printf("\t Info: Area and Contour Length \n");
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for( size_t i = 0; i< contours.size(); i++ )
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{
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printf(" * Contour[%d] - Area (M_00) = %.2f - Area OpenCV: %.2f - Length: %.2f \n", (int)i, mu[i].m00, contourArea(contours[i]), arcLength( contours[i], true ) );
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Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );
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drawContours( drawing, contours, (int)i, color, 2, 8, hierarchy, 0, Point() );
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circle( drawing, mc[i], 4, color, -1, 8, 0 );
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}
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}
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