How to use form validation with the file uploader to make sure a file is uploaded
// The following are just examples from the documentation...
$config['upload_path'] = './uploads/';
$config['allowed_types'] = 'gif|jpg|png';
$config['max_size'] = '100';
$config['max_width'] = '1024';
$config['max_height'] = '768';
// ... other preferences as necessary