Template Matching(Image Searching) for multiple objects - 반복되는 이미지 모두 찾기

Template matching is a technique for finding areas of an image that match (are similar) to a template image (patch).

OpenCV matchTemplate 함수와 threshold 값을 이용해 이미지에서 찾고 싶은 부분을 검색해 모두 찾을 수 있다.

2019/07/08 - [Software/OpenCV] - Template Matching(Image Searching) - 부분 이미지 검색

2019/07/12 - [Software/OpenCV] - Template Matching(Image Searching) with a mask for multiple objects - 마스크를 이용해 (배경이 다른) 반복되는 이미지 모두 찾기

<Target>

<Source>

Below code explains how to spot multiple objects with a threshold. Adjust threshold value if it doesn't work properly.

• Type of the template matching operation: TM_SQDIFF_NORMED

• Threshold: 0.00015

#include <opencv2/opencv.hpp>
#include <time.h>
 
using namespace cv;
using namespace std;
 
int main()
{
    clock_t start, end;
    double minVal;
    Point minLoc;
    double threshold = 0.00015;
    int count = 0;
 
    Mat FinalImage = imread("source.jpg", IMREAD_COLOR);
    if (FinalImage.empty())
        return -1;
 
    // Grayscale source and target for faster calculation.
    Mat SourceImage;
    cvtColor(FinalImage, SourceImage, CV_BGR2GRAY);
 
    Mat TargetImage = imread("target.jpg", IMREAD_GRAYSCALE);
    if (TargetImage.empty())
        return -1;
 
    Mat Result;
 
    start = clock();
    matchTemplate(SourceImage, TargetImage, Result, TM_SQDIFF_NORMED); // Type of the template matching operation: TM_SQDIFF_NORMED
    minMaxLoc(Result, &minVal, NULL, &minLoc, NULL);
 
    for (int i = 0; i < Result.rows; i++)
        for (int j = 0; j < Result.cols; j++)
            if (Result.at<float>(i, j) < threshold)
            {
                rectangle(FinalImage, Point(j, i), Point(j + TargetImage.cols, i + TargetImage.rows), Scalar(0, 0, 255), 1);
                count++;
            }
    end = clock();
 
    cout << "Searching time: " << difftime(end, start) / CLOCKS_PER_SEC << endl;
    cout << "Minimum Value: " << minVal << " " << minLoc << endl;
    cout << "Threshold: " << threshold << endl;
    cout << "Found: " << count << endl;
 
    imshow("TargetImage", TargetImage);
    imshow("Result", Result);
    imshow("FinalImage", FinalImage);
 
    waitKey(0);
 
    return 0;
}

<Result>

Found 4 coins in 0.035 secs.