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Keypoint matching.


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#include <opencv2/opencv.hpp>
 
using namespace std;
using namespace cv;
 
int main(int argc, char** argv)
{
    Mat trg = imread("Target.jpg", IMREAD_GRAYSCALE);
    Mat src = imread("Source.jpg", IMREAD_GRAYSCALE);
    
    if (trg.empty() || src.empty()) {
        cerr << "Image load failed!" << endl;
        
        return -1;
    }
 
    Ptr<Feature2D> feature = ORB::create();
    
    vector<KeyPoint> trgKeypoints, srcKeypoints;
    Mat trgDesc, srcDesc;
    feature->detectAndCompute(trg, Mat(), trgKeypoints, trgDesc);
    feature->detectAndCompute(src, Mat(), srcKeypoints, srcDesc);
    // Detects keypoints and computes the descriptors.
 
    Ptr<DescriptorMatcher> matcher = BFMatcher::create(NORM_HAMMING);
    // Brute-force matcher create method.
 
    vector<DMatch> matches;
    // Class for matching keypoint descriptors.
    matcher->match(trgDesc, srcDesc, matches);
    // Finds the best match for each descriptor from a query set.
 
    sort(matches.begin(), matches.end());
    vector<DMatch> good_matches(matches.begin(), matches.begin() + 100);
 
    Mat dst;
    drawMatches(trg, trgKeypoints, src, srcKeypoints, good_matches, dst,
        Scalar::all(-1), Scalar(-1), vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS);
    // Draws the found matches of keypoints from two images.
 
    imshow("dst", dst);
 
    waitKey();
    
    return 0;
}




100 best matches.


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Posted by J-sean
:
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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

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#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(00255), 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;
}
cs




<Result>


Found 4 coins in 0.035 secs.




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Posted by J-sean
:
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Template matching is a technique for finding areas of an image that match (are similar) to a template image (patch).


Python Pillow library로 구현해 봤던 Image searching 기술을 OpenCV matchTemplate 함수로 간단히 만들 수 있다.


2018/11/30 - [Software/Python] - Pillow 이미지 서치(Image Search) 1

2018/12/02 - [Software/Python] - Pillow 이미지 서치(Image Search) 2

2019/07/10 - [Software/OpenCV] - Template Matching(Image Searching) for multiple objects - 반복되는 이미지 모두 찾기

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>




Type of the template matching operation: TM_SQDIFF

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#include <opencv2/opencv.hpp>
#include <time.h>
 
using namespace cv;
using namespace std;
 
int main()
{
    clock_t start, end;
    double minVal;
    Point minLoc;
 
    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); // Type of the template matching operation: TM_SQDIFF
    normalize(Result, Result, 01, NORM_MINMAX, -1, Mat());
    minMaxLoc(Result, &minVal, NULL&minLoc, NULL);
    end = clock();
 
    cout << "Searching time: " << difftime(end, start) / CLOCKS_PER_SEC << endl;
    cout << "Minimum Value: " << minVal << endl << "Location: " << minLoc << endl;
    rectangle(FinalImage, minLoc, Point(minLoc.x + TargetImage.cols, minLoc.y + TargetImage.rows), Scalar(00255), 1);
 
    imshow("TargetImage", TargetImage);
    imshow("Result", Result);
    imshow("FinalImage", FinalImage);
 
    waitKey(0);
 
    return 0;
}
cs


<Result>


Found the target at the husky's front paw in 0.014 secs.



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Posted by J-sean
: