ch08 perspective

#python

import cv2
import numpy as np

src = None
srcPts = np.zeros((4, 2), dtype=np.float32)
dstPts = np.zeros((4, 2), dtype=np.float32)

def on_mouse(event, x, y, flags, param):
    global src, srcPts
    cnt = param[0]

    if event == cv2.EVENT_LBUTTONDOWN:
        if cnt < 4:
            srcPts[cnt] = [x, y]
            cnt += 1

            cv2.circle(src, (x, y), 5, (0, 0, 255), -1)
            cv2.imshow("src", src)

            if cnt == 4:
                w, h = 200, 300

                dstPts[0] = [0, 0]
                dstPts[1] = [w - 1, 0]
                dstPts[2] = [w - 1, h - 1]
                dstPts[3] = [0, h - 1]

                pers = cv2.getPerspectiveTransform(srcPts, dstPts)

                dst = cv2.warpPerspective(src, pers, (w, h))

                cv2.imshow("dst", dst)

cv2.namedWindow("src")
cv2.setMouseCallback("src", on_mouse, [0])

src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch08\\perspective\\card.bmp")

if src is None:
    print("Image load failed!")
else:
    cv2.imshow("src", src)
    cv2.waitKey(0)

cv2.destroyAllWindows()

---

// C++

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

using namespace cv;
using namespace std;

Mat src;
Point2f srcPts[4], dstPts[4];

void on_mouse(int event, int x, int y, int flags, void* userdata);

int main()
{
	src = imread("card.bmp");

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

	namedWindow("src");
	setMouseCallback("src", on_mouse);

	imshow("src", src);
	waitKey(0);

	return 0;
}

void on_mouse(int event, int x, int y, int flags, void*)
{
	static int cnt = 0;

	if (event == EVENT_LBUTTONDOWN) {
		if (cnt < 4) {
			srcPts[cnt++] = Point2f(x, y);

			circle(src, Point(x, y), 5, Scalar(0, 0, 255), -1);
			imshow("src", src);

			if (cnt == 4) {
				int w = 200, h = 300;

				dstPts[0] = Point2f(0, 0);
				dstPts[1] = Point2f(w - 1, 0);
				dstPts[2] = Point2f(w - 1, h - 1);
				dstPts[3] = Point2f(0, h - 1);

				Mat pers = getPerspectiveTransform(srcPts, dstPts);

				Mat dst;
				warpPerspective(src, dst, pers, Size(w, h));

				imshow("dst", dst);
			}
		}
	}
}

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

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