How Can I Sort Images

<?php
$directory = 'server/php/files/';
$thumbsdir = 'server/php/files/thumbnail';
$allowed_types=array('jpg','jpeg','gif','png');
$file_parts=array();
$ext='';
$title='';
$i=0;

$files = scandir($directory); foreach($files as $file)
{
	if($file=='.' || $file == '..') continue;
	$file_parts = explode('.',$file);
	$ext = strtolower(array_pop($file_parts));

	$title = implode('.',$file_parts);
	$title = htmlspecialchars($title);
	
	$nomargin='';
	
	if(in_array($ext,$allowed_types))
	{
		if(($i+1)%4==0) $nomargin='nomargin';
	
		echo '
		<div class="pic '.$nomargin.'" style="background:removed('.$thumbsdir.'/'.$file.') no-repeat 50% 50%; margin-removed19px;">
		<a href="'.$directory.'/'.$file.'" title="'.$title.'" target="_blank">'.$title.'</a>
		</div>';
		
		$i++;
		
	}
}

closedir($dir_handle);

?>