se returns the alpha.</span></div><div class="line"><a name="l00262"></a><span class="lineno">  262</span>&#160;<span class="keyword">template</span> &lt;<span class="keyword">typename</span> Pixel&gt;</div><div class="line"><a name="l00263"></a><span class="lineno">  263</span>&#160;<span class="keyword">auto</span> alpha_or_max(Pixel <span class="keyword">const</span>&amp; p) -&gt; <span class="keyword">typename</span> channel_type&lt;Pixel&gt;::type</div><div class="line"><a name="l00264"></a><span class