[Kendall]

I would loop through the files and look at their extensions:

$dir = '/tmp';
$dh  = opendir($dir);
while (false !== ($fileName = readdir($dh))) {
    $ext = substr($fileName, strrpos($fileName, '.') + 1);
    if(in_array($ext, array("jpg","jpeg","png","gif")))
        $files1[] = $fileName;
}