CONTROLLER
class ImagesController extends AppController {
    var $name = 'Images';
    var $uses = array('Image','Person');
    var $helpers = array('Html', 'Form');
        function add($idp = 0, $mac = 0) 
        {
            if (!empty($this->data) &&
                 is_uploaded_file($this->data['Image']['File']['tmp_name'])) {
                $fileData = fread(fopen($this->data['Image']['File']['tmp_name'], "r"),
                                         $this->data['Image']['File']['size']);
                $this->data['Image']['name'] = $this->data['Image']['File']['name'];
                $this->data['Image']['type'] = $this->data['Image']['File']['type'];
                $this->data['Image']['size'] = $this->data['Image']['File']['size'];
                $this->data['Image']['data'] = $fileData;
                $this->data['Image']['people_id'] = $idp;
                $this->Image->save($this->data);
                $this->redirect(array('controller' => 'People', 'action' => 'welcome',$mac));   
            }
        }
When I validate the form, I lose both parameters $idp and $mac.. How can I make them persist?
VIEW
<?php
    echo $form->create('Image', array('action' => 'add', 'type' => 'file'));
    echo $form->file('File');
    echo $form->submit('Upload');
    echo $form->end();
?>