Following code will retrieve all file names from a specified folder.

<?php
$filePath = "/var/www/public_html/mysite/images";/* Enter path to the folder */
$string="";
$fileCount=0;
$dir = opendir($filePath); 
while ($file = readdir($dir)) { 
if (eregi("\.png",$file)) { /* Look for files with .png extension */
$string .= "$file<br />";
$fileCount++;
}
}
if ($fileCount > 0) {
echo sprintf("<h2>All Files in %s</h2><br />%s<strong>Total Files: %s</strong>",$filePath,$string,$fileCount);
}
?>