/span> BlueChannel, <span class="keyword">typename</span> GrayChannelValue&gt;
<a name="l00071"></a><a class="code" href="g_i_l_0519.html">00071</a> <span class="keyword">struct </span><a class="code" href="g_i_l_0519.html" title="red * .3 + green * .59 + blue * .11 + .5">rgb_to_luminance_fn</a> {
<a name="l00072"></a>00072     GrayChannelValue operator()(<span class="keyword">const</span> RedChannel&amp; red, <span class="keyword">const</span> GreenChannel&amp; green, <span class="keyword">const</span> Blu