opencv 比较图片

Mat img1 = Highgui.imread("storage/external_SD/a.png");Mat img2 = Highgui.imread("storage/external_SD/b.png");MatOfKeyPoint keypoints1 = new MatOfKeyPoint();MatOfKeyPoint keypoints2 = new MatOfKeyPoint();Mat descriptors1 = new Mat();Mat descriptors2 = new Mat();//Definition of ORB keypoint detector and descriptor extractorsFeatureDetector detector = FeatureDetector.create(FeatureDetector.ORB); DescriptorExtractor extractor = DescriptorExtractor.create(DescriptorExtractor.ORB);//Detect keypointsdetector.detect(img1, keypoints1);detector.detect(img2, keypoints2);  //Extract descriptorsextractor.compute(img1, keypoints1, descriptors1);extractor.compute(img2, keypoints2, descriptors2);//Definition of descriptor matcherDescriptorMatcher matcher = DescriptorMatcher.create(DescriptorMatcher.BRUTEFORCE_HAMMING);//Match points of two imagesMatOfDMatch matches = new MatOfDMatch();matcher.match(descriptors1,descriptors2 ,matches);