Call one controller from another controller

[eluser]Unknown[/eluser]
Sorry if this is a n00b question but I'm having a hard time wrapping my head around this...

I have a site controller, this is responsible for gathering required data and loading views (Queries are hard coded while I'm testing):

Code:

class Site extends Controller {

function userView() {
        $this->load->model('image_model');

        if ($query = $this->image_model->getAlbumsByUser(2)) {
            $data['albums'] = $query;
        }

        $this->load->view('header');
        $this->load->view('user_view', $data);
        $this->load->view('footer');
    }

I also have a user controller which manages logging in etc.

Code:

class User extends Controller {

    function login() {

        $username = $this->input->post('username');
        $password = $this->input->post('password');

        $this->load->model('user_model');

        if ($this->user_model->authenticateUser($username, $this->_prepPassword($password))) {

            $sessiondata = array(
                'username' => $username,
                'authenticated' => true
            );

            $this->session->set_userdata($sessiondata);
            $this->load->view('user_view'); ***********************
        }
    }

Where the stars are I want to load the user_view, but as this view relies on certain data being passed to it, I want to load it by first calling Site->userView(). How do I achieve this? Or am I not understanding MVC properly?

[eluser]WanWizard[/eluser]
After validating the login, store the logged-in state in the session, and use redirect to load the site controller.

[eluser]Prophet[/eluser]
Can't User just load image_model? I wouldn't be too concerned with code repetition, especially simple stuff like loading views.

Code:

class User extends Controller {

    function login() {

        $username = $this->input->post('username');
        $password = $this->input->post('password');

        $this->load->model('user_model');
        $this->load->model('image_model'); //Autoload it if you call it often

        if ($this->user_model->authenticateUser($username, $this->_prepPassword($password))) {

            if ($query = $this->image_model->getAlbumsByUser(2)) {
                $data['albums'] = $query;
            }

            $sessiondata = array(
                'username' => $username,
                'authenticated' => true
            );

            $this->session->set_userdata($sessiondata);
            $this->load->view('user_view', $data);
        }
    }

Edit: If you really want to call Site->userView() from User, just have User extend Site (since Site sounds like it would have some generic methods that will be useful to many controllers throughout the site?)