docs: public double getSkewAngle() {
          ImageDeskew.HoughLine[] hl;
          double sum = 0.0;
          int count = 0;
  
          // perform Hough Transformation
          calc();
          // top 20 of the detected lines in the image
          hl = getTop(20);
  
          if (hl.length >= 20) {
              // average angle of the lines
              for (int i = 0; i < 19; i++) {
                  sum += hl[i].alpha;
                  count++;
              }
              return (sum / count);
          } else {
              return 0.0d;
          }
      }