code: public function rotate( $angle, $background = 'FFFFFF' )
      {
          $angle = intval( $angle );
          if ( !is_int( $angle ) || $angle < 0 || $angle > 360 )
          {
              throw new ezcBaseValueException( 'height', $angle, 'int > 0 && int < 360' );
          }
  
          $resource = $this->getActiveResource();
  
          $bg = $this->bgArrayFromHex( $background );
          $gdBackgroundColor = imagecolorallocatealpha( $resource, $bg['r'], $bg['g'], $bg['b'], $bg['a'] );
  
          $newResource = ImageRotate( $resource, $angle, $gdBackgroundColor );
          if ( $newResource === false )
          {
              throw new ezcImageFilterFailedException( 'rotate', 'Rotation of image failed.' );
          }
  
          imagedestroy( $resource );
          $this->setActiveResource( $newResource );
      }
docs: /* (non-PHPdoc)
  @see extension/ezie/autoloads/eziezc/interfaces/eZIEEzcConversions#rotate($angle, $color)