Copy the images to the public folder after form submit with PLupload in a custom module
I finally manage to do what I want...

I didn't understand how to use file_copy ans its $destination argument. We can put a file path, not only a folder path. So, I can save my file.jpg correctly.

My code :

$values = $form_state['values']['create'];
$photos_count = count($values['photos']);
for ($i = 0; $i &lt; $photos_count; $i++) {
    $path = $values['photos'][$i]['tmppath'];
    $name = $values['photos'][$i]['name'];
    // set file datas as an object to pass it in file_copy()
    $file = (object)array(
        'uid' =&gt; 0,
        'uri' =&gt; $path,
        'filemime' =&gt; file_get_mimetype($path),
        'status' =&gt; 1
    );
    // copy the file in the correct folder
    if ($file = file_copy($file, $filepath . '/' . $name)) {
        drupal_set_message('Success');
    } else {
        drupal_set_message('Error', 'error');
    }
    // set the field datas for saving the node with an array
    $node-&gt;field_album_photos[$node-&gt;language][$i] = (array)$file;
}


Have a nice day !