Image manipulation & cache

[eluser]Bondie[/eluser]
Is there a way of caching the dynamically generated images created with the image manipulation class or am I wasting my time?

Here is my simple code, it's messy I know, I need to tidy it up:

Code:

<?php

    class Assets extends CI_Controller{
        
        public function img ($method = 'resize', $w = 'original', $h = 'original', $src = '') {
            define("IMG_PATH", "assets/images/");
                        
            if ($src != NULL && !file_exists(IMG_PATH.$src)) {
                show_404();
            } else {                
                $config['image_library'] = 'gd2';
                $config['source_image'] = IMG_PATH.$src;
                $config['create_thumb'] = FALSE;
                $config['maintain_ratio'] = TRUE;
                $config['quality'] = '100%';
                if($w != 'original') $config['width'] = $w;
                if($h != 'original') $config['height'] = $h;
                $config['dynamic_output'] = TRUE;
                
                $this->load->library('image_lib', $config);

                if ( ! $this->image_lib->resize())
                {
                    echo $this->image_lib->display_errors();
                }
                
                $this->image_lib->clear();
            }
            
        }
        
    }

Some guidance and advice would be much appreciated!

EDIT
An example url would be:

www.example.com/assets/img/resize/100/100/picture.jpg