ss="pre">PixelLocatorConcept</span></code> - a memory-based locator,
<code class="docutils literal"><span class="pre">memory_based_2d_locator</span></code> and a virtual locator <code class="docutils literal"><span class="pre">virtual_2d_locator</span></code>.</p>
<p>The <code class="docutils literal"><span class="pre">memory_based_2d_locator</span></code> is a locator over planar or interleaved images
that have their pixels in memory. It takes a model of <code class="docutils literal"><span class="pre">Ste