code: protected double[][] extractFeaturesInternal(BufferedImage image) {
  		double[][] features = super.extractFeaturesInternal(image);
  		for (int i = 0; i < features.length; i++) {
  			Normalization.normalizePower(features[i], 0.5);
  			Normalization.normalizeL2(features[i]);
  		}
  		return features;
  	}
docs: Detects key points inside the image and computes descriptions at those points.