How do I show the number of images attached to a post on the image attachment page?

Question

I use the image attachment page to show images attached to a post one by one, in a slideshow sort of affect. I'd like to be able to display the total number of images attached to the parent post and the number of the particular image that's being shown on any given attachment page so you see the picture and the words "Image 3 of 15" for example.

Update... I was able to get the total number to show using this code:

<?php 
  global $post;
  $attachments = get_children( array( 'post_parent' => $post->post_parent, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC', 'orderby' => 'menu_order ID' ) );
  $count = count( $attachments );
  echo $count; 
?>

I still can't figure out how to show the number of the current image.
Anyone have any suggestions?

Update 2...

Greenie's answer got me almost there but it's outputting all the numbers at once:

"Image 1 of 8Image 2 of 8Image 3 of 8Image 4 of 8Image 5 of 8Image 6 of 8Image 7 of 8Image 8 of 8"

Here is the code I used:

global $post;
$attachments = get_children( array( 'post_parent' => $post->post_parent, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC', 'orderby' => 'menu_order ID' ) );
$count = count( $attachments );
$currentImage = 1;
foreach ($attachments as $attachment) {
   // output your image here
   echo "Image ". $currentImage . " of ". $count; 
   $currentImage++; 
}

What's going wrong?

Update 3 - THE ANSWER!

global $post;
$attachments = get_children( array( 'post_parent' => $post->post_parent, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC', 'orderby' => 'menu_order ID' ) );

$count = count( $attachments );
$specific = array();
$i = 1;

foreach ( $attachments as $attachment ) {
    $specific[$attachment->ID] = $i;
    ++$i;
}

echo "Image {$specific[$post->ID]} of {$count}";

Answer 1

This works:

global $post;
$attachments = get_children( array( 'post_parent' => $post->post_parent, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => 'ASC', 'orderby' => 'menu_order ID' ) );

$count = count( $attachments );
$specific = array();
$i = 1;

foreach ( $attachments as $attachment ) {
    $specific[$attachment->ID] = $i;
    ++$i;
}

echo "Image {$specific[$post->ID]} of {$count}";

Answer 2

Add something like this to the above code:

$currentImage = 1;
foreach ($attachments as $attachment) {
   // output your image here
   echo "Image ". $currentImage . " of ". $count; 
   $currentImage++; 
}

Answer 3

If you are looking for a plugin to manage image gallery, you can use attachments plugin,

http://wordpress.org/plugins/attachments/

It keeps the gallery separate and does not put the image gallery shortcodes in post content, thus providing you with full hold over image display in your post/page/custom post. You can also change the order of your images by just drag-n-drop

here is a sample code of how to retrieve your gallery images,

<?php $attachments = new Attachments( 'attachments' ); /* pass the instance name */ ?>
<?php if( $attachments->exist() ) : ?>
  <h3>Attachments</h3>
  <p>Total Attachments: <?php echo $attachments->total(); ?></p>
  <ul>
    <?php while( $attachments->get() ) : ?>
      <li>
        ID: <?php echo $attachments->id(); ?><br />
        Type: <?php echo $attachments->type(); ?><br />
        Subtype: <?php echo $attachments->subtype(); ?><br />
        URL: <?php echo $attachments->url(); ?><br />
        Image: <?php echo $attachments->image( 'thumbnail' ); ?><br />
        Source: <?php echo $attachments->src( 'full' ); ?><br />
        Size: <?php echo $attachments->filesize(); ?><br />
        Title Field: <?php echo $attachments->field( 'title' ); ?><br />
        Caption Field: <?php echo $attachments->field( 'caption' ); ?>
      </li>
    <?php endwhile; ?>
  </ul>
<?php endif; ?>