You can do this using hook_preprocess_node()
either in your theme's template.php file, or a custom module file. You'll want to use API functions to get the data from the node rather than accessing the arrays directly, so you don't need to worry about language codes etc.
function MYTHEME_preprocess_node(&$vars) {
$node = $vars['node'];
if ($node->type == 'the_type' && $vars['view_mode'] == 'full') {
$field_items = field_get_items('node', $node, 'field_name');
if (!empty($field_items)) {
$filenames = array();
foreach ($field_items as $item) {
$filenames[] = $item['filename'];
}
$vars['filenames'] = theme('item_list', array('items' => $filenames));
}
}
}
You can obviously change the output to whatever HTML you need, but the above will produce an unordered list of image filenames, available in the $filenames
variable in your node.tpl.php file.