code: protected double[][] extractFeaturesInternal(BufferedImage image) {
  
  		double[][] descriptions = harder(image);
  		if (!perBandNormalization) {
  			// if perBandNormalization is off then do a final L2 normalization
  			for (int i = 0; i < descriptions.length; i++) {
  				Normalization.normalizeL2(descriptions[i]);
  				// SurfDescribeOps.normalizeFeatures(descriptions[i]);
  			}
  		}
  		return descriptions;
  	}
docs: Detects key points inside the image and computes descriptions at those points. <br>