protected function imageFlipVertical ()
	{
		$x_i = imagesx($this->workingImage);
	    $y_i = imagesy($this->workingImage);

	    for ($x = 0; $x < $x_i; $x++) 
		{
	        for ($y = 0; $y < $y_i; $y++) 
			{
	            imagecopy($this->workingImage, $this->workingImage, $x, $y_i - $y - 1, $x, $y, 1, 1);
	        }
	    }
	}