Building thumbnails dynamicly in PHP

One problem Ive always hated was creating lots of thumbnails for images. So instead I created a PHP wrapper for the command line imagemagick tools.

This script requires Cana_Thumb which you can get on github:

class Cana_Thumb {
  private $_path;
  private $_cache;
  private $_watermark;
  private $_img;
  private $_im;

  public function __construct($params = array()) {

    if (file_exists('/usr/local/bin/convert')) {
      $this->_im = '/usr/local/bin/convert';
    } elseif(file_exists('/usr/bin/convert')) {
      $this->_im = '/usr/bin/convert';
    } elseif(file_exists('/opt/local/bin/convert')) {
      $this->_im = '/opt/local/bin/convert';
    } else {
      throw new Exception('Could not find imagemagick');

    if ($this->_im && isset($params['img'])) {