 b_out_sum += (pb = stackOut.b)

          r_in_sum -= pr
          g_in_sum -= pg
          b_in_sum -= pb

          stackOut = stackOut.next

          yi += <span class="number">4</span>
          
        yw += width
        
      <span class="keyword">for</span> x <span class="keyword">in</span> [<span class="number">0.</span>..width]
        g_in_sum = b_in_sum = r_in_sum = g_sum = b_sum = r_sum = <span class="number">0</span>

        yi = x &lt;&lt; <span class="number">2</span>
        r_out_sum 