OpencvMaskTest.java

import org.opencv.core.*;
import org.opencv.features2d.DescriptorExtractor;
import org.opencv.features2d.DescriptorMatcher;
import org.opencv.features2d.FeatureDetector;
import org.opencv.features2d.Features2d;
import org.opencv.highgui.Highgui;

/**
 * Created by Marcin on 2014-11-04.
 */
public class OpencvMaskTest {

    static {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    }

    //setup SIFT detector and SIFT extractor
    static DescriptorExtractor siftDescriptor = DescriptorExtractor.create(DescriptorExtractor.SIFT);
    static FeatureDetector siftDetector = FeatureDetector.create(FeatureDetector.PYRAMID_SIFT);

    public static void main(String[] args) {

        // read images as Mat
        Mat first = Highgui.imread("Cabildo_Catedralicio_(1913),_de_Refugio_Reyes_Rivas.jpg");
        Mat second = Highgui.imread("Cabildo_Catedralicio_(1913),_de_Refugio_Reyes_Rivas_1.jpg");
        
        //detect keyPoints
        MatOfKeyPoint keyPointsFirst = getKeyPoints(first);
        MatOfKeyPoint keyPointsSecond = getKeyPoints(second);

        // calculate descriptors
        Mat descriptorsFirst = getDescriptor(first, keyPointsFirst);
        Mat descriptorsSecond = getDescriptor(second, keyPointsSecond);

        //match points
        MatOfDMatch matOfDMatch = getMatOfMatchedPoints(descriptorsFirst, descriptorsSecond);

        MatOfByte mask = new MatOfByte(new byte[matOfDMatch.height()]);
        Mat output = new Mat();
        Features2d.drawMatches(
                first, keyPointsFirst,
                second, keyPointsSecond,
                matOfDMatch,
                output,
                Scalar.all(-1), Scalar.all(-1),
                mask, // MASK!!!!!!!!!!!!!!!!
                Features2d.NOT_DRAW_SINGLE_POINTS
        );
        Highgui.imwrite("matched.jpg", output);
    }

    public static MatOfKeyPoint getKeyPoints(Mat image) {
        MatOfKeyPoint keyPoints = new MatOfKeyPoint();
        siftDetector.detect(image, keyPoints);
        return keyPoints;
    }

    public static Mat getDescriptor(Mat image, MatOfKeyPoint keyPoints) {
        Mat descriptor = new Mat();
        siftDescriptor.compute(image, keyPoints, descriptor);
        return descriptor;
    }

    public static MatOfDMatch getMatOfMatchedPoints(Mat descriptorsFirst, Mat descriptorsSecond) {
        MatOfDMatch matOfDMatch = new MatOfDMatch();
        DescriptorMatcher descriptorMatcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE_SL2);
        descriptorMatcher.match(descriptorsFirst, descriptorsSecond, matOfDMatch);
        return matOfDMatch;
    }
}