 class="code" href="structboost_1_1gil_1_1detail_1_1rgb__to__luminance__fn.html">rgb_to_luminance_fn</a>&lt;uint8_t,uint8_t,uint8_t, GrayChannelValue&gt; {</div><div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;    GrayChannelValue operator()(uint8_t red, uint8_t green, uint8_t blue)<span class="keyword"> const </span>{</div><div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;        <span class="keywordflow">return</span> channel_convert&lt;GrayChannelV