import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfKeyPoint;
import org.opencv.highgui.Highgui;
import org.opencv.features2d.*;
public class ExtractSIFT
{
 public static void main( String[] args )
 {
    System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
    Mat test_mat = Highgui.imread("pfau.jpg");
    Mat desc = new Mat();
    FeatureDetector fd = FeatureDetector.create(FeatureDetector.SIFT);
    MatOfKeyPoint mkp =new MatOfKeyPoint();
    fd.detect(test_mat, mkp);
    DescriptorExtractor de = DescriptorExtractor.create(DescriptorExtractor.SIFT);
    de.compute(test_mat,mkp,desc );//提取sift特征
    System.out.println(desc.cols());
    System.out.println(desc.rows());
 
 }
}