OpenCV study notes (14) to create a border for the spin box and elliptical profile

https://docs.opencv.org/3.4/de/d62/tutorial_bounding_rotated_ellipses.html

 

Does not rotate

 

 

 

 

#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;
Mat src_gray;
int thresh = 100;
RNG rng(12345);
void thresh_callback(int, void*);
int main(int argc, char** argv)
{
//	CommandLineParser parser(argc, argv, "{@input | stuff.jpg | input image}");
	Mat src = imread("p1.png");
	if (src.empty())
	{
		cout << "Could not open or find the image!\n" << endl;
		cout << "usage: " << argv[0] << " <Input image>" << endl;
		return -1;
	}
	cvtColor(src, src_gray, COLOR_BGR2GRAY);
	blur(src_gray, src_gray, Size(3, 3));
	const char* source_window = "Source";
	namedWindow(source_window,0);
	imshow(source_window, src);
	const int max_thresh = 255;
	createTrackbar("Canny thresh:", source_window, &thresh, max_thresh, thresh_callback);
	thresh_callback(0, 0);
	waitKey();
	return 0;
}
void thresh_callback(int, void*)
{
	Mat canny_output;
	Canny(src_gray, canny_output, thresh, thresh * 2);
	vector<vector<Point> > contours;
	findContours(canny_output, contours, RETR_TREE, CHAIN_APPROX_SIMPLE);
	vector<vector<Point> > contours_poly(contours.size());
	vector<Rect> boundRect(contours.size());
	vector<Point2f>centers(contours.size());
	vector<float>radius(contours.size());
	for (size_t i = 0; i < contours.size(); i++)
	{
		approxPolyDP(contours[i], contours_poly[i], 3, true);
		boundRect[i] = boundingRect(contours_poly[i]);
		minEnclosingCircle(contours_poly[i], centers[i], radius[i]);
	}
	Mat drawing = Mat::zeros(canny_output.size(), CV_8UC3);
	for (size_t i = 0; i< contours.size(); i++)
	{
		Scalar color = Scalar(rng.uniform(0, 256), rng.uniform(0, 256), rng.uniform(0, 256));
		drawContours(drawing, contours_poly, (int)i, color);
		rectangle(drawing, boundRect[i].tl(), boundRect[i].br(), color, 2);
		circle(drawing, centers[i], (int)radius[i], color, 2);
	}
	namedWindow("Contours", 0);
	imshow("Contours", drawing);
}

　　

 

　　Rotating  https://docs.opencv.org/3.4/de/d62/tutorial_bounding_rotated_ellipses.html

 

 

 

#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;
Mat src_gray;
int thresh = 100;
RNG rng(12345);
void thresh_callback(int, void* );
int main( int argc, char** argv )
{
    CommandLineParser parser( argc, argv, "{@input | stuff.jpg | input image}" );
    Mat src = imread( samples::findFile( parser.get<String>( "@input" ) ) );
    if( src.empty() )
    {
        cout << "Could not open or find the image!\n" << endl;
        cout << "Usage: " << argv[0] << " <Input image>" << endl;
        return -1;
    }
    cvtColor( src, src_gray, COLOR_BGR2GRAY );
    blur( src_gray, src_gray, Size(3,3) );
    const char* source_window = "Source";
    namedWindow( source_window );
    imshow( source_window, src );
    const int max_thresh = 255;
    createTrackbar( "Canny thresh:", source_window, &thresh, max_thresh, thresh_callback );
    thresh_callback( 0, 0 );
    waitKey();
    return 0;
}
void thresh_callback(int, void* )
{
    Mat canny_output;
    Canny( src_gray, canny_output, thresh, thresh*2 );
    vector<vector<Point> > contours;
    findContours( canny_output, contours, 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( contours[i] );
        if( contours[i].size() > 5 )
        {
            minEllipse[i] = fitEllipse( contours[i] );
        }
    }
    Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
    for( size_t i = 0; i< contours.size(); i++ )
    {
        Scalar color = Scalar( rng.uniform(0, 256), rng.uniform(0,256), rng.uniform(0,256) );
        // contour
        drawContours( drawing, contours, (int)i, color );
        // ellipse
        ellipse( drawing, minEllipse[i], color, 2 );
        // 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 );
        }
    }
    imshow( "Contours", drawing );
}