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Hello I am new to opencv library and I have a code to process two images if they are same. But at end of the code i can't get good result, such as if images are same or not. Thanks for your help! and this is the code:

public class TemplateMatching { static int fw; static int fh; static String yo; public int run(String inFile, String templateFile) {

    // System.out.println("\nRunning Template Matching");

    Mat img = Highgui.imread(inFile);
    Mat templ = Highgui.imread(templateFile);

FeatureDetector  fd = FeatureDetector.create(FeatureDetector.SURF); 
final MatOfKeyPoint keyPointsLarge = new MatOfKeyPoint();
final MatOfKeyPoint keyPointsSmall = new MatOfKeyPoint();

fd.detect(img, keyPointsLarge);
fd.detect(templ, keyPointsSmall);

// System.out.println("keyPoints.size() : "+keyPointsLarge.size()); //System.out.println("keyPoints2.size() : "+keyPointsSmall.size());

Mat descriptorsLarge = new Mat();
Mat descriptorsSmall = new Mat();

DescriptorExtractor extractor = DescriptorExtractor.create(DescriptorExtractor.BRIEF);
extractor.compute(img, keyPointsLarge, descriptorsLarge);
extractor.compute(templ, keyPointsSmall, descriptorsSmall);

// System.out.println("descriptorsA.size() : "+descriptorsLarge.size()); // System.out.println("descriptorsB.size() : "+descriptorsSmall.size());

MatOfDMatch matches = new MatOfDMatch();

DescriptorMatcher matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE_HAMMINGLUT);
matcher.match(descriptorsLarge, descriptorsSmall, matches);

//System.out.println("matches.size() : "+matches.size());

MatOfDMatch matchesFiltered = new MatOfDMatch();

List<DMatch> matchesList = matches.toList();
List<DMatch> bestMatches= new ArrayList<DMatch>();

Double max_dist = 0.0;
Double min_dist = 100.0;

for (int i = 0; i < matchesList.size(); i++)
{
    Double dist = (double) matchesList.get(i).distance;

    if (dist < min_dist && dist != 0)
    {
        min_dist = dist;
    }

    if (dist > max_dist)
    {
        max_dist = dist;
    }

}

 // System.out.println("max_dist : "+max_dist);

// System.out.println("min_dist : "+min_dist);

if(min_dist > 50 )
{
   // System.out.println("No match found");
  //  System.out.println("Just return ");
    return -1;
}

double threshold = 3 * min_dist;
double threshold2 = 2 * min_dist;

if (threshold > 75)
{
    threshold  = 75;
}
else if (threshold2 >= max_dist)
{
    threshold = min_dist * 1.1;
}
else if (threshold >= max_dist)
{
    threshold = threshold2 * 1.4;
}

//System.out.println("Threshold : "+threshold);

for (int i = 0; i < matchesList.size(); i++)
{
    Double dist = (double) matchesList.get(i).distance;

    if (dist < threshold)
    {
        bestMatches.add(matches.toList().get(i));
        //System.out.println(String.format(i + " best match added : %s", dist));
    }
}
matchesFiltered.fromList(bestMatches);

//System.out.println("matchesFiltered.size() : " + matchesFiltered.size());

if(matchesFiltered.rows() >=21)
{
    //System.out.println("match found");
    return 1;
}
else
{
    return -1;
}

} }