ion step - one for the end
condition of the loop using the iterators, and one inside
<code class="docutils literal"><span class="pre">iterator_from_2d::operator++</span></code> to determine whether we are at the end of a
row. For fast operations, such as pixel copy, this second check adds about
15% performance delay (measured for interleaved images on Intel platform).
GIL overrides some STL algorithms, such as <code class="docutils literal"><span class="pre">std::copy</span></code> and <code class="docutils