 when grouping letters.</li>
  <li><strong>intensity_thresh</strong>: the allowable intensity variance when grouping letters.</li>
  <li><strong>distance_ratio</strong>: the allowable distance variance when grouping letters.</li>
  <li><strong>intersect_ratio</strong>: the allowable intersect variance when grouping letters.</li>
  <li><strong>elongate_ratio</strong>: the allowable elongate variance when grouping letters.</li>
  <li><strong>letter_thresh</strong>: the allowable letter threshold.</li>
  <li><