最完美的匹配网页中图片 src 部分的正则表达式

$str=‘<p style="padding: 0px; margin-top: 0px; margin-bottom: 0px; line-height: 200%;"><img border="0" src="upfiles/2009/07/1246430143_4.jpg" /></p><p style="padding: 0px; margin-top: 0px; margin-bottom: 0px; line-height: 200%;"><img border="0" src=\‘upfiles/2009/07/1246430143_3.jpg\‘ /></p><p style="padding: 0px; margin-top: 0px; margin-bottom: 0px; line-height: 200%;"><img border="0" src="upfiles/2009/07/1246430143_1.jpg" /><img width="280" height="187"  class="imgloading" original="http://s.yoututuan.com/team/2011/1206/13231497847660.jpg" src="http://s.yoututuan.com/team/2011/1206/13231497847660.jpg" style="display: block; ">‘;

    $pattern="/<img.*?src=[‘|\"](.*?(?:\.(?:gif|jpg)))[‘|\"].*?[\/]?>/i";
    preg_match_all($pattern,$str,$match);

    echo ‘<pre>‘;
    print_r($match);