public function rotate( $angle, $background = 'FFFFFF' )
    {
        $angle = intval( $angle );
        if ( !is_int( $angle ) || ( $angle < 0 ) || ( $angle > 360 ) )
        {
            throw new ezcBaseValueException( 'height', $height, 'angle < 0 or angle > 360' );
        }

        $angle = 360 - $angle;
        $background = "#{$background}";

        $this->addFilterOption(
            $this->getActiveReference(),
            '-background',
            $background
        );

        $this->addFilterOption(
            $this->getActiveReference(),
            '-rotate',
            $angle
        );
    }