code: public function horizontalFlip( $region = null )
      {
          $resource = $this->getActiveResource();
  
          if ( $region )
          {
              $newResource = $this->region( "horizontalFlipImg", $resource, $region );
          }
          else
          {
              $newResource = $this->horizontalFlipImg( $resource );
          }
  
          $this->setActiveResource( $newResource );
      }
docs: /* (non-PHPdoc)
  @see extension/ezie/autoloads/eziezc/interfaces/eZIEEzcConversions#horizontalFlip($region)