GD library

yes

imagecreate(W,H)

extension=php_gd2.dll

you need to open an extension for gdlibrary in the php.ini 
file. and then use simple image functions as suggested by 
Munesh

image creating functions

dir() 

Example :-

<?php
//Open images directory
$dir = dir("images");//List files in images directory
while (($file = $dir->read()) !== false)
{
echo "filename: " . $file . "<br />";
}$dir->close();
?>