protected function verifyFormatCompatiblity ()
	{
		$isCompatible 	= true;
		$gdInfo			= gd_info();
		
		switch ($this->format)
		{
			case 'GIF':
				$isCompatible = $gdInfo['GIF Create Support'];
				break;
			case 'JPG':
				$isCompatible = (isset($gdInfo['JPG Support']) || isset($gdInfo['JPEG Support'])) ? true : false;
				break;
			case 'PNG':
				$isCompatible = $gdInfo[$this->format . ' Support'];
				break;
			default:
				$isCompatible = false;
		}
		
		if (!$isCompatible)
		{
			// one last check for "JPEG" instead
			$isCompatible = $gdInfo['JPEG Support'];
			
			if (!$isCompatible)
			{
				$this->triggerError('Your GD installation does not support ' . $this->format . ' image types');
			}
		}
	}