Java openCV - after using Imgproc.matchTemplate method, how do i examine the result?

Question

i am calling:

Imgproc.matchTemplate(image, templ, result, 0);

and the result of the match is in a Mat instance. I couldn't find any documentation for this class. If i understand right, the result contains a matrix of probabilities. How can i find the Maximum of the probabilities? I can't even understand how a Mat instance looks like and what it contains.

Thanks Eyal

Answer 1

lena.png:

pattern.png:

class MatchingDemo {
    public void run(String inFile, String templateFile, String outFile,
            int match_method) {
        System.out.println("\nRunning Template Matching");

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

        // / Create the result matrix
        int result_cols = img.cols() - templ.cols() + 1;
        int result_rows = img.rows() - templ.rows() + 1;
        Mat result = new Mat(result_rows, result_cols, CvType.CV_32FC1);

        // / Do the Matching and Normalize
        Imgproc.matchTemplate(img, templ, result, match_method);
        Core.normalize(result, result, 0, 1, Core.NORM_MINMAX, -1, new Mat());
        Highgui.imwrite("out2.png", result);

        // / Localizing the best match with minMaxLoc
        MinMaxLocResult mmr = Core.minMaxLoc(result);

        Point matchLoc;
        if (match_method == Imgproc.TM_SQDIFF
                || match_method == Imgproc.TM_SQDIFF_NORMED) {
            matchLoc = mmr.minLoc;
            System.out.println(mmr.minVal);
        } else {
            matchLoc = mmr.maxLoc;
            System.out.println(mmr.maxVal);
        }

        // / Show me what you got
        Core.rectangle(img, matchLoc, new Point(matchLoc.x + templ.cols(),
                matchLoc.y + templ.rows()), new Scalar(0, 255, 0));

        // Save the visualized detection.
        System.out.println("Writing " + outFile);
        Highgui.imwrite(outFile, img);

    }
}

public class TemplateMatching {
    public static void main(String[] args) {
        System.loadLibrary("opencv_java249");
        new MatchingDemo().run("lena.png", "pattern.png", "output.png", Imgproc.TM_CCOEFF);
    }
}