public void testExtraction() throws IOException {
   JpegCoefficientHistogram acc = new JpegCoefficientHistogram();
   BufferedImage image = ImageIO.read(new FileInputStream(testFilesPath + testFiles[0]));
   System.out.println("image = " + image.getWidth() + " x " + image.getHeight());
   acc.extract(image);
   System.out.println("acc = " + acc.getStringRepresentation());
 }
 public void testPerformance() throws IOException {
   long ms, sum = 0;
   for (int i = 0; i < sampleQueries.length; i++) {
     int id = sampleQueries[i];
     System.out.println("id = " + id + ": ");
     String file = testExtensive + "/" + id + ".jpg";
     JpegCoefficientHistogram acc = new JpegCoefficientHistogram();
     BufferedImage image = ImageIO.read(new FileInputStream(file));
     ms = System.currentTimeMillis();
     acc.extract(image);
     ms = System.currentTimeMillis() - ms;
     sum += ms;
     System.out.println(
         "the same? " + acc.getStringRepresentation().equals(acc.getStringRepresentation()));
   }
   System.out.println("time per image = " + sum / sampleQueries.length);
   System.out.println("sum = " + sum);
 }