Use image as “Edit post” button

EDIT:
These forum can’t display my last solution (the manual one). Here again:

<a href="<?php bloginfo('url'); ?>/wp-admin/page.php?action=edit&post=<?php the_ID(); ?>">
       <img src="<?php bloginfo('stylesheet_directory'); ?>/icons/page_edit.png" title="Edit this page"></a>

Can’t anybody help me? Please, I really need to get this to work!

It’s working now with this code:

function get_ID() {
	global $wp_query;
	$thePostID = $wp_query->post->ID;
	return $thePostID;
}

and

<?php bloginfo('url'); ?>/wp-admin/page.php?action=edit&post=<?php echo get_ID(); ?> as link.