3"></a><span class="lineno">   73</span>&#160;</div><div class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;<span class="comment">// performance specialization for unsigned char</span></div><div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> GrayChannelValue&gt;</div><div class="line"><a name="l00076"></a><span class="lineno">   76</span>&#160;<span class="keyword">struct </span><a