Using PHP Curl to Post Images to Drupal site

I have reviewed the tutorials and snippets on the Drupal site (http://drupal.org/node/87711) and I have read several discussions about the topic. Yet I'm still having trouble.

After using PHP/Curl to login, I move to the node/add/image page and get the token no problem. But I'm having trouble posting a new image node. I can get everything working when posting a new page node with Curl. It's just posting a new image node that's giving me trouble.

Here is the code that should add the new image node. Curl fills out most of the image form fields such as title, body etc. All fields are populated by Curl EXCEPT the image file upload. And this seems to be what's stopping curl from creating the new image node. What am I doing wrong? How can I get Curl to fill in the file upload field?

$ch = curl_init();
curl_setopt($ch, CURLOPT_HEADER, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_COOKIEFILE, "cookie.txt");
curl_setopt($ch, CURLOPT_URL,"http://www.example.com/?q=node/add/image/");
curl_setopt($ch, CURLOPT_POST, 1);


$postarray = array(
'files[image]' =>@$file,
'taxonomy[3]'=>'2',
  'title' => $file,
  'body' => 'xxxx',
'status' => '1',
'revision' => '1',
'comment' => '2',
'name' => 'mov',
'moderate' => '0',
  'form_id' => 'image_node_form',
'form_token' => $token,
  'op' => 'Submit'

  );

curl_setopt($ch, CURLOPT_POSTFIELDS, $postarray);


$buf2 = curl_exec ($ch);

curl_close ($ch);