[fw-general] outputting image from controller private function

[water]

I was trying to output a an image from a controller's private function such 
that:
http://host/app/controller/action/
would return an image.

I would need to reset the header's content type but I'm still having problems 
(in browser error returned below). I've included some comments on various 
things I tried. My code looks like this:

public function somethingAction(){
        //ob_start();

        $this->_helper->viewRenderer->setNoRender();
        $this->_helper->layout->disableLayout();


    if($this->_generate('play.html',$data)){
            $this->_success();
    }else{
            $this->_failure();
            //echo "failure<br/>";
    }
}

private function _success(){
        $file_name = "/data/sites/site/www/docs/fadmin/images/ok.gif";
        
        
        if(ob_get_length()){
            ob_end_flush();
            exit;
        }
        /*
        $this->_response->setHeader('Content-type', 'image/gif'); 
          $this->_response->setHeader('Cache-Control', 'no-cache');         
        */
        header('Content-type: image/gif');
        header("Cache-control: private, no-cache");  
        header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); # Past date
        header("Pragma: no-cache");    
            
        
        echo fread(fopen($file_name, 'rb'), filesize($file_name));
        /*
        ob_end_flush();
        
        $data = file_get_contents($file_name);
        
        $this->_response->setBody($data);
        */
        ob_end_flush();
        
    }

The error I get in the browser is:


Any help with this would be greatlly appreciated.

thanks,

jonathan