Updating show_authors() to eliminate Subscribers

I have been working on show_authors() codebase and found that I can not remove the Subscribers from the output of this loop. Any suggestions on how to only post Roles aside from Subscriber?

<?php
	// display all users with a link to their user page
	function show_authors() {
	global $wpdb;
	$users = $wpdb->get_col("SELECT * FROM $wpdb->users ORDER BY user_nicename");
	foreach($users as $user) {
		$user = get_userdata($user);
		echo '<li><img src="/wp-content/authors/' . $user->user_login . '-5.jpg" alt="" /><span class="author-name">' . $user->display_name . '</span><br /><span class="author-company">' .  TruncateString($user->user_url, 26) . '</span><br/<a href="/index.php?author=' . $user->ID . '">View Profile &raquo;</a></li>';
	}
}
?>