de/d62/tutorial_bounding_rotated_ellipses.html

 #include "opencv2/imgcodecs.hpp"

 #include "opencv2/highgui/highgui.hpp"

 #include "opencv2/imgproc/imgproc.hpp"

 #include <iostream>

 #include <stdio.h>

 #include <stdlib.h>


 using namespace cv;

 using namespace std;


 Mat src; Mat src_gray;

 int thresh = 100;

 int max_thresh = 255;

 RNG rng(12345);


 void thresh_callback(int, void* );


 int main( int, char** argv )

 {

   src = imread( argv[1], 1 );


   cvtColor( src, src_gray, COLOR_BGR2GRAY );

   blur( src_gray, src_gray, Size(3,3) );


   const char* source_window = "Source";

   namedWindow( source_window, WINDOW_AUTOSIZE );

   imshow( source_window, src );


   createTrackbar( " Threshold:", "Source", &thresh, max_thresh, thresh_callback );

   thresh_callback( 0, 0 );


   waitKey(0);

   return(0);

 }


 void thresh_callback(int, void* )

 {

   Mat threshold_output;

   vector<vector<Point> > contours;

   vector<Vec4i> hierarchy;


   threshold( src_gray, threshold_output, thresh, 255, THRESH_BINARY );

   findContours( threshold_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) );


   vector<RotatedRect> minRect( contours.size() );

   vector<RotatedRect> minEllipse( contours.size() );


   for( size_t i = 0; i < contours.size(); i++ )

      { minRect[i] = minAreaRect( Mat(contours[i]) );

        if( contours[i].size() > 5 )

          { minEllipse[i] = fitEllipse( Mat(contours[i]) ); }

      }


   Mat drawing = Mat::zeros( threshold_output.size(), CV_8UC3 );

   for( size_t i = 0; i< contours.size(); i++ )

      {

        Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );

        // contour

        drawContours( drawing, contours, (int)i, color, 1, 8, vector<Vec4i>(), 0, Point() );

        // ellipse

        ellipse( drawing, minEllipse[i], color, 2, 8 );

        // rotated rectangle

        Point2f rect_points[4]; minRect[i].points( rect_points );

        for( int j = 0; j < 4; j++ )

           line( drawing, rect_points[j], rect_points[(j+1)%4], color, 1, 8 );

      }


   namedWindow( "Contours", WINDOW_AUTOSIZE );

   imshow( "Contours", drawing );

 }

cv::Scalar
Scalar_< double > Scalar
Definition: types.hpp:597

cv::blur
void blur(InputArray src, OutputArray dst, Size ksize, Point anchor=Point(-1,-1), int borderType=BORDER_DEFAULT)
Blurs an image using the normalized box filter.

cv::cvtColor
void cvtColor(InputArray src, OutputArray dst, int code, int dstCn=0)
Converts an image from one color space to another.

highgui.hpp

cv::imread
Mat imread(const String &filename, int flags=IMREAD_COLOR)
Loads an image from a file.

cv::Mat::zeros
static MatExpr zeros(int rows, int cols, int type)
Returns a zero array of the specified size and type.

cv::imshow
void imshow(const String &winname, InputArray mat)
Displays an image in the specified window.

cv::minAreaRect
RotatedRect minAreaRect(InputArray points)
Finds a rotated rectangle of the minimum area enclosing the input 2D point set.

imgcodecs.hpp

cv::ellipse
void ellipse(InputOutputArray img, Point center, Size axes, double angle, double startAngle, double endAngle, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0)
Draws a simple or thick elliptic arc or fills an ellipse sector.

cv::drawContours
void drawContours(InputOutputArray image, InputArrayOfArrays contours, int contourIdx, const Scalar &color, int thickness=1, int lineType=LINE_8, InputArray hierarchy=noArray(), int maxLevel=INT_MAX, Point offset=Point())
Draws contours outlines or filled contours.

cv::Point_< float >

cv::createTrackbar
int createTrackbar(const String &trackbarname, const String &winname, int *value, int count, TrackbarCallback onChange=0, void *userdata=0)
Creates a trackbar and attaches it to the specified window.

cv::RETR_TREE
Definition: imgproc.hpp:409

cv::line
void line(InputOutputArray img, Point pt1, Point pt2, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0)
Draws a line segment connecting two points.

imgproc.hpp

cv::Mat::size
MatSize size
Definition: mat.hpp:1882

cv::namedWindow
void namedWindow(const String &winname, int flags=WINDOW_AUTOSIZE)
Creates a window.

cv::THRESH_BINARY

Definition: imgproc.hpp:309

cv::Size
Size2i Size
Definition: types.hpp:308

i
for i
Definition: modelConvert.m:63

cv::RNG
Random Number Generator.
Definition: core.hpp:2600

CV_8UC3
#define CV_8UC3
Definition: cvdef.h:118

cv::CHAIN_APPROX_SIMPLE
Definition: imgproc.hpp:421

cv::threshold
double threshold(InputArray src, OutputArray dst, double thresh, double maxval, int type)
Applies a fixed-level threshold to each array element.

cv::WINDOW_AUTOSIZE
Definition: highgui.hpp:138

cv::fitEllipse
RotatedRect fitEllipse(InputArray points)
Fits an ellipse around a set of 2D points.

cv::findContours
void findContours(InputOutputArray image, OutputArrayOfArrays contours, OutputArray hierarchy, int mode, int method, Point offset=Point())
Finds contours in a binary image.

main
int main(int argc, const char *argv[])
Definition: facerec_demo.cpp:67

cv::Scalar_< double >

cv::Mat
n-dimensional dense array class
Definition: mat.hpp:726

cv::Point
Point2i Point
Definition: types.hpp:181

cv::COLOR_BGR2GRAY
convert between RGB/BGR and grayscale, color conversions
Definition: imgproc.hpp:511

cv::waitKey
int waitKey(int delay=0)
Waits for a pressed key.