code: private void initArrays() {
          if (data == null || picsize != data.length) {
              data = new int[picsize];
              magnitude = new int[picsize];
  
              xConv = new float[picsize];
              yConv = new float[picsize];
              xGradient = new float[picsize];
              yGradient = new float[picsize];
          }
      }
docs: private utility methods