Rewriting URL's in codeigniter with url_title()?

I am rewriting my website with codeigniter and have something I want to do but not sure it is possible.

I have a gallery on my site powered by the Flickr API. Here is an example of the code I use to display the Landscape pictures:

<?php foreach ($landscapes->photoset->photo as $l->photoset->photo) : ?>  
  <a href="<?=$l->photoset->photo->farm?>/<?=$l->photoset->photo->server?>/<?=$l->photoset->photo->id?>/<?=$l->photoset->photo->secret?>/<?=$l->photoset->photo->title?>">  
    <img class="f_thumb" src="<?=$l->photoset->photo->farm?>.static.flickr.com/<?=$l->photoset->photo->server?>/<?=$l->photoset->photo->id ?>_<?=$l->photoset->photo->secret ?>_s.jpg" title="<?=$l->photoset->photo->title?>" alt="<?=$l->photoset->photo->title?>" />
  </a>  
<?php endforeach; ?>

As you can see when a user clicks on a picture I pass over the Farm, Server, ID, Secret and Title elements using URI segments and build the page in the controller using

$data['farm'] = $this->uri->segment(3); 
$data['server'] = $this->uri->segment(4); 
$data['id'] = $this->uri->segment(5); 
$data['secret'] = $this->uri->segment(6);
$data['title'] = $this->uri->segment(7);

Everything works and is fine, but the URL’s are a tad long. Example:

http://localhost:8888/wip/index.php/gallery/focus/3/2682/4368875046/e8f97f61d9/Old_Mill_House_in_Donegal

Is there a way to rewrite the URL so its more like:

http://localhost:8888/wip/index.php/gallery/focus/Old_Mill_House_in_Do开发者_JAVA百科negal

I was looking at using:

$url_title = $this->uri->segment(7);
$url_title = url_title($url_title, 'underscore', TRUE);

But I can’t seem to be able to get it to work. Any ideas?

Are the links linking internally? Or are they linking to flickr? If it's internally, I'd suppose you could pass all the requisite information via POST. If it's to flickr, I don't think there is a way you can control how they want requests to come in for a specific item.

What's the endgame/purpose of all that extra info (secret, server, etc)?