ch12 polygon

#python 

import cv2
import numpy as np

def set_label(img, pts, label):
    rc = cv2.boundingRect(pts)
    cv2.rectangle(img, rc, (0, 0, 255), 1)
    cv2.putText(img, label, rc[:2], cv2.FONT_HERSHEY_PLAIN, 1, (0, 0, 255))

def main():
    img = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch12\\polygon\\polygon.bmp", cv2.IMREAD_COLOR)

    if img is None:
        print("Image load failed!")
        return -1

    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    _, bin = cv2.threshold(gray, 200, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)

    contours, _ = cv2.findContours(bin, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)

    for pts in contours:
        if cv2.contourArea(pts) < 400:
            continue

        approx = cv2.approxPolyDP(pts, cv2.arcLength(pts, True) * 0.02, True)
        vtc = len(approx)

        if vtc == 3:
            set_label(img, pts, "TRI")
        elif vtc == 4:
            set_label(img, pts, "RECT")
        else:
            length = cv2.arcLength(pts, True)
            area = cv2.contourArea(pts)
            ratio = 4.0 * np.pi * area / (length * length)

            if ratio > 0.85:
                set_label(img, pts, "CIR")

    cv2.imshow("img", img)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

if __name__ == "__main__":
    main()

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// C++

#include "opencv2/opencv.hpp"
#include <iostream>

using namespace cv;
using namespace std;

void setLabel(Mat& img, const vector<Point>& pts, const String& label)
{
	Rect rc = boundingRect(pts);
	rectangle(img, rc, Scalar(0, 0, 255), 1);
	putText(img, label, rc.tl(), FONT_HERSHEY_PLAIN, 1, Scalar(0, 0, 255));
}

int main(int argc, char* argv[])
{
	Mat img = imread("polygon.bmp", IMREAD_COLOR);

	if (img.empty()) {
		cerr << "Image load failed!" << endl;
		return -1;
	}

	Mat gray;
	cvtColor(img, gray, COLOR_BGR2GRAY);

	Mat bin;
	threshold(gray, bin, 200, 255, THRESH_BINARY_INV | THRESH_OTSU);

	vector<vector<Point>> contours;
	findContours(bin, contours, RETR_EXTERNAL, CHAIN_APPROX_NONE);

	for (vector<Point> pts : contours) {
		if (contourArea(pts) < 400)
			continue;

		vector<Point> approx;
		approxPolyDP(pts, approx, arcLength(pts, true)*0.02, true);

		int vtc = (int)approx.size();

		if (vtc == 3) {
			setLabel(img, pts, "TRI");
		} else if (vtc == 4) {
			setLabel(img, pts, "RECT");
		} else {
			double len = arcLength(pts, true);
			double area = contourArea(pts);
			double ratio = 4. * CV_PI * area / (len * len);

			if (ratio > 0.85) {
				setLabel(img, pts, "CIR");
			}
		}
	}

	imshow("img", img);

	waitKey(0);
	return 0;
}

C++ Code 출처 : OpenCV 4로 배우는 컴퓨터 비전과 머신 러닝 - 황선규 저

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