Fridrix,
$open=opendir('sys/img');
while($file=readdir($open)){
$ext=strtolower(pathinfo($file, PATHINFO_EXTENSION));
if ($ext == 'png' || $ext == 'jpg' || $ext == 'jpeg' || $ext == 'gif'){
echo '<img src="/sys/img/'.$file.'">";
}
}
closedir($open);