code: public static function filter( $region )
      {
          $r = array(
              'x'      => intval( $region['x'] ),
              'y'      => intval( $region['y'] ),
              'width'  => intval( $region['w'] ),
              'height' => intval( $region['h'] ) 
          );
          return array( new ezcImageFilter( 'crop', $r ) );
      }
docs: Creates a crop filter
  
  @param  array(int) $region Affected region, as a 4 keys array: w, h, x, y
  @return array( ezcImageFilter )