>typename</span> mpl::if_c&lt;is_mutable, ref_t, value_type&gt;::type                  reference;
<a name="l00360"></a>00360         <span class="keyword">typedef</span> reference                                                                result_type;
<a name="l00361"></a>00361 
<a name="l00362"></a>00362         <a class="code" href="g_i_l_0515.html" title="Function object that returns a grayscale reference of the N-th channel of a given...">nth_channel_deref_fn</a>(<span class="keywordtype">int</span>