><span class="lineno">  257</span>&#160;}</div><div class="line"><a name="l00258"></a><span class="lineno">  258</span>&#160;</div><div class="line"><a name="l00259"></a><span class="lineno">  259</span>&#160;} <span class="comment">// namespace detail</span></div><div class="line"><a name="l00260"></a><span class="lineno">  260</span>&#160;</div><div class="line"><a name="l00261"></a><span class="lineno">  261</span>&#160;<span class="comment">// Returns max_value if the pixel has no alpha channel. Otherwi