Get Image Tag From a String

The code below can get the img tag from a static string, like this :

/img/portrait.gif?t=1451961935000" align="absmiddle
http://www.example.com/ssss.jpg

function Allimg($str)
{
    $pattern = "/<[img|IMG].*?src=[\'|\"](.*?(?:[\.gif|\.jpg|\.png|\.bmp|\.jpeg]))[\'|\"].*?[\/]?>/";
    preg_match_all($pattern, $str, $match);
    $_count = count($match[1]);
    $_html = '';
    if ($_count>0) {
        for ($i = 0; $i < $_count; $i++) {
            $_html = $_html . $match[1][$i];
            $_html = $_html . '<br>';
        }
    }
    return $_html;
}