ch12 labeling

#python 

import cv2
import numpy as np

def labeling_basic():
    data = np.array([
        [0, 0, 1, 1, 0, 0, 0, 0],
        [1, 1, 1, 1, 0, 0, 1, 0],
        [1, 1, 1, 1, 0, 0, 0, 0],
        [0, 0, 0, 0, 0, 1, 1, 0],
        [0, 0, 0, 1, 1, 1, 1, 0],
        [0, 0, 0, 1, 0, 0, 1, 0],
        [0, 0, 1, 1, 1, 1, 1, 0],
        [0, 0, 0, 0, 0, 0, 0, 0]
    ], dtype=np.uint8) * 255

    src = data.astype(np.uint8)

    cnt, labels = cv2.connectedComponents(src)

    print("src:\n", src)
    print("labels:\n", labels)
    print("number of labels:", cnt)

def labeling_stats():
    src = cv2.imread("D:\\projects\\SampleCode\\006939-master\\ch12\\labeling\\keyboard.bmp", cv2.IMREAD_GRAYSCALE)

    if src is None:
        print("Image load failed!")
        return

    _, bin = cv2.threshold(src, 0, 255, cv2.THRESH_BINARY | cv2.THRESH_OTSU)

    cnt, labels, stats, centroids = cv2.connectedComponentsWithStats(bin)

    dst = cv2.cvtColor(src, cv2.COLOR_GRAY2BGR)

    for i in range(1, cnt):
        if stats[i, cv2.CC_STAT_AREA] < 20:
            continue

        x, y, w, h = stats[i, cv2.CC_STAT_LEFT], stats[i, cv2.CC_STAT_TOP], stats[i, cv2.CC_STAT_WIDTH], stats[i, cv2.CC_STAT_HEIGHT]
        cv2.rectangle(dst, (x, y), (x + w, y + h), (0, 255, 255), 2)

    cv2.imshow("src", src)
    cv2.imshow("dst", dst)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

def main():
    labeling_basic()
    labeling_stats()

if __name__ == "__main__":
    main()

src:
 [[  0   0 255 255   0   0   0   0]
 [255 255 255 255   0   0 255   0]
 [255 255 255 255   0   0   0   0]
 [  0   0   0   0   0 255 255   0]
 [  0   0   0 255 255 255 255   0]
 [  0   0   0 255   0   0 255   0]
 [  0   0 255 255 255 255 255   0]
 [  0   0   0   0   0   0   0   0]]
labels:
 [[0 0 1 1 0 0 0 0]
 [1 1 1 1 0 0 2 0]
 [1 1 1 1 0 0 0 0]
 [0 0 0 0 0 3 3 0]
 [0 0 0 3 3 3 3 0]
 [0 0 0 3 0 0 3 0]
 [0 0 3 3 3 3 3 0]
 [0 0 0 0 0 0 0 0]]
number of labels: 4

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// C++

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

using namespace cv;
using namespace std;

void labeling_basic();
void labeling_stats();

int main()
{
	labeling_basic();
	labeling_stats();

	return 0;
}

void labeling_basic()
{
	uchar data[] = {
		0, 0, 1, 1, 0, 0, 0, 0,
		1, 1, 1, 1, 0, 0, 1, 0,
		1, 1, 1, 1, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 1, 1, 0,
		0, 0, 0, 1, 1, 1, 1, 0,
		0, 0, 0, 1, 0, 0, 1, 0,
		0, 0, 1, 1, 1, 1, 1, 0,
		0, 0, 0, 0, 0, 0, 0, 0,
	};

	Mat src = Mat(8, 8, CV_8UC1, data) * 255;

	Mat labels;
	int cnt = connectedComponents(src, labels);

	cout << "src:\n" << src << endl;
	cout << "labels:\n" << labels << endl;
	cout << "number of labels: " << cnt << endl;
}

void labeling_stats()
{
	Mat src = imread("keyboard.bmp", IMREAD_GRAYSCALE);

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

	Mat bin;
	threshold(src, bin, 0, 255, THRESH_BINARY | THRESH_OTSU);

	Mat labels, stats, centroids;
	int cnt = connectedComponentsWithStats(bin, labels, stats, centroids);

	Mat dst;
	cvtColor(src, dst, COLOR_GRAY2BGR);

	for (int i = 1; i < cnt; i++) {
		int* p = stats.ptr<int>(i);
		
		if (p[4] < 20) continue;

		rectangle(dst, Rect(p[0], p[1], p[2], p[3]), Scalar(0, 255, 255));
	}


	imshow("src", src);
	imshow("dst", dst);

	waitKey();
	destroyAllWindows();
}

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

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